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PHOTO-LITHOGRAPHY 


BY 

GEORG FRITZ 

I P 

( Vice-Director of the Imperial State Printing Works at Vienna} 


TRANSLATED BY 

E. J. WALL 

(Fellow of the Royal Photographic Society ) 


Copyright, 1S96, by G. Gennkrt. 



1896. 

NEW YORK: 

G. GENNERT, PUBLISHER, 
24 & 26 East 13th St. 

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J M r . 

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THE AUTHOR’S PREFACE. 


Photo-lithography, with its many branches and its extended 
application, when used direct and also as handmaid for the 
lithographer and printer from stone, is, with the exception of 
phototypy and autotypy, indeed that process for the preparation 
of letterpress plates which has done the most towards making 
photography useful for the graphic arts, in the artistic sense as 
well as from the practical point of view. And in the near future 
it will be a great acquisition when it is once generally recognized 
that colour plates can be prepared by photographic means without 
any considerable amount of manual or artistic help. It is the 
more to be wondered at that photo-lithography has not yet found 
that extension and general use which it in so high a degree 
deserves. 

I have written this book, impressed with the urgency of 
stimulating the propagation of this useful process. In writing I 
have been careful to avoid all those details which are for the 
practical worker of minor interest—the description of the 
historical evolution, etc., so instructive as these must certainly be 
—so that I have abstained from many complicated and un¬ 
intelligible formulae. I leave this willingly to a more ready 
writer. Starting rather from the standpoint of speaking as a 
practical worker to practical men, I have recorded all the 
experience which I have gained in the course of many years. 

Should it occur to me in the future that it was my task to have 
treated all photo-lithographic processes, with all their ramifica¬ 
tions, in the most complete manner, I have still the consciousness 
of having described as completely as possible the practical 
processes, and think that I have thus been useful to many workers, 


2 


PREFACB. 


and I dare saj with absolute certainty that only tested and tried 
formulae have been noticed in this book. 

With the earnest wish that this book may be received with a 
fraction of the goodwill with which I have worked at the writing 
of the same, I present it to the technical world. 

GEORG FRITZ. 

Vienna. 


On receiving this work for review I was greatly struck with the 
thoroughly practical manner in which it was written, and thought 
than an English translation might be acceptable to the large and 
ever increasing class of photo-mechanical workers who might not 
otherwise have the opportunity of reading it in the original. I 
have kept to the author’s text as close as is consistent with the 
idiomatic construction of German. 

I am indebted to Messrs. Hazell, Watson and Viney for permis¬ 
sion to undertake the task of translating the work for another firm 
of publishers, and I hope the translation may prove as acceptable 
and useful to the readers as it has been pleasurable to me to 
do it. 

E. J. WALL 

L, Creed Lane, 

London, E.C. 



INTRODUCTION, 


1 .—The theory of printing from stone. He who would study or 
practise photo-lithography must first become acquainted with the 
fundamental principles on which lithography rests. I find it 
therefore necessary to first give in concise form a small treatise 
on the theory of this process as well as on the most important 
materials which are necessary in the practice of the same. 

The theoretical principle of lithography is purely chemical, and 
is based principally on the repulsion of water and other sub¬ 
stances by fatty bodies, and the alteration of these greasy bodies 
by acids. As the support for this chemical opposition a stone or 
zinc plate is used, which are sufficiently porous to allow grease, 
w'ater, acid, and certain resinous solutions to penetrate to a certain 
degree. 

The fatty substances which are transferred to the stone by 
writing, drawing, or transfer, are autographic ink, lithographic 
ink, and chalk, the so-called transfer and photo-lithographic 
colours. There are also other substances, which are used 
especially in photo-lithography, which do not evidently penetrate 
the stone and which cannot be considered as greasy substances, 
but which, as we shall see later on, have exactly the same action. 

The above-mentioned fatty substances actually penetrate the 
porous stone and make it in places suitable to take more printing 
ink. By the so-called etching—dilute nitric acid mixed with 
gum water—two effects are produced. On the one hand the 
fatty bodies are altered in chemical composition, being decomposed 
into the fatty acids which combine intimately with the material 
of the stone—calcium carbonate. On the other hand, the surface 
of the stone not covered with the fatty substances is chemically 
changed, since the carbonate of lime is converted into nitrate, 
which has now the property of keeping moderately damp when 
moistened with water, and thus repelling grease. If such a 
transfer of greasy bodies on to the stone is allowed to act fcr some 
hours, and the fatty substances are removed with turpentine, it 
will be seen that these places have a lighter colour than the other 
parts of the surface of the stone, and if the stone be rolled up 
with a leather roller, charged with a greasy ink, after the stone 


4 


PHOTO-LITHOGRAPH Y. 


has beeu damped, only these places will take the greasy ink. By 
means of a litho steam or hand press prints can then be prepared 
from this. 

It is frequently necessary to make corrections or additions to the 
drawing on the stone ; if tho stone has been already etched some 
means must be used which will remove the action of the etching, or 
else the stone will not take the greasy matter, or at least not so 
readily as is desirable. Very weak acetic acid, about 1-2 per cent., 
will do this. If the stone is flowed over with this dilute acetic 
acid or dilute table vinegar, the action of the stronger nitric acid 
and the gum is stopped, and the surface of the stone will again 
take fatty matter. 

Before the penetration of the grease the stone is prepared by 
polishing with a concentrated solution of oxalic acid. Oxalic acid 
poured on to the stone would exert an etching action, but make the 
stone to a certain degree capable of taking the ink. If this liquid is 
rubbed on the stone with a cloth or linen pad with moderate 
pressure, the stone receives a high polish—especially the hard 
kinds—and in this condition the stone takes the ink well, like any 
flat object, but will not retain it. If a transfer is made on to such 
a stone, and the same etched, the image will completely disappear 
the first time the roller passes over it. This polish can be re¬ 
moved with 1 or 2 per cent, acetic acid, and the stone then has its 
primitive qualities. This method is used to reverse the image, 
which will be described later on. 

2 .—Litho stone is dense limestone of the mountain limestone 
group, and is found in the Tertiary deposits at a depth of 
two to three metres. Its constituents are lime, clay, and silicious 
earths, combined with carbonic acid, but lime is in the preponder¬ 
ance ; it only contains a very small proportion of silica. In the 
stronger acids litho stone dissolves completely. The varieties of 
very fine stalactitic chalk of tolerable hardness, with flat shell-like 
fracture, without rust spots, glassy crystals or impurities, and those 
with very even grain, are the most useful for photo-lithography. 
Marble, which consists of pure chalk, cannot be used for litho¬ 
graphy because, on account of its greater density, the greasy matter 
cannot penetrate so deeply, and therefore such stones would give 
only a few pulls. 

The commercial litho stones are of different colours, from 
whitish yellow to greenish shining grey. The latter has a finer and 
more even grain, and is considerably harder than the other kind. 
These two kinds are briefly designated in the trade as “ yellow ” 
and “blue,” and the brighter kinds are, as a rule, softer and 
cheaper than the darker. 

The faults which the stones sometimes show differ considerably, 
and these produce certain inconveniences in continuous work. 
Many stones have dark and light spots, and as these spots have, as 
a rule, different densities, the etching solution cannot exert the 


INTRODUCTION. 


same action over the whole of the stone, and consequently in fine 
drawings, autotypes, etc., there are formed bright and dark 
spots. This also occurs with calcareous, speckled and marbly 
stones. The very bright stones have less density, and therefore 
suck up the damping solution-very quickly, and begin with re¬ 
peated printing to become tinted. Stones with calcareous or 
rusty veins will split easily, especially in the large sizes. Lime 
spots or lime veins, which are easily recognized by their brighter 
color, take in graining a very unequal grain. The drawing is 
darker on these places, since the grain is greater according to the 
softness of the stone. Such stones are unsuitable for those photo¬ 
lithographic processes in which graining is used, such as the pro¬ 
cesses of Orell and Fussli and Bartos. The so-called glass veins 
and glass spots are crystallizations consisting of silicon, and are 
harder than the other parts of the stone. On these places the 
fatty inks do not penetrate deep enough; the drawing does 
not adhere well and can be easily removed by the rollers. 

The hard stones receive a much finer surface than the soft 
when polished with pumice stone; they also reproduce every 
point, line and detail of the drawing much more delicately, 
finer and .sharper; and lastly, they have the advantage that they 
etch much more evenly, and re-etching is easy if moderate care be 
taken. 

For the finer photo-lithographic work, if quality and con¬ 
tinuous working is desired, only the good “blue” stones should 
be used; for cheaper line drawings “yellow” stones free from 
faults may be used. 

3 .—Zinc plates may be used instead of stones, especially in 
large establishments, but have not proven a decided success. 
Their treatment before and during printing is essentially different 
to that of the stones, yet so far as regards this method of print¬ 
ing they come very nearly equal to stones. At first smooth 
polished zinc plates were used, but in consequence of some diffi¬ 
culty in using them, and the great care necessary in choosing 
them, they have been almost replaced by the prepared or oxidized 
plates. 

Zincographic processes differ essentially in the preparation of 
the plates. In the one, the plate is given a coating which has a 
similar composition to a litho stone; in the other, the plate is 
roughened and given a fine grain by a mechanical method, such 
as the sandblast, in order that it may be then oxidized by a chem¬ 
ical process, with acids or alkalies. All these processes are more 
or less advantageous. The zinc plates cost about one-tenth to 
one-twentieth of the cost of the stones, and this may well be suf¬ 
ficient grounds for the proprietors of large establishments being 
interested in zinc plates, as the stones are rather costly. 

Excellent zinc plates, coated with a film or merely oxidized, 
can be procured commercially in the United States. For those 


6 


PH OTO-L1TIIO.GR A PH Y. 


who wish to prepare their own plates the following tested 
formulae are given:— 

A zinc plate from 1 to 1.5 mm. thick is roughened by means of 
the sandblast till it has a fine, even grain and appears smooth, 
but clean. The following solution is prepared 


Concentrated solution of alum . 20 parts 

Phosphoric acid . 2 

Water . 20 “ 

or 

Alum solution 10 parts 

Gallic acid . 15 “ 

Nitric acid . 2 “ / ( ~ 

Water 30 “ 


The roughened plate is first flowed over with water, and im¬ 
mediately afterwards, with one of the above solutions, in the 
same way as a plate, is covered with a developer. The plate is 
oxidized by this, and there is formed on the surface a white pre¬ 
cipitate. It is then washed thoroughly under a rose tap and 
dried, and the plate may be either coated with a light sensitive 
substance for printing or a transfer be made on to it. 

After the development or the transfer, the plate is gummed 
and then etched with an etching solution consisting of— 

Gallic acid . 10 parts 

Phosphoric acid . 2 “ 

Gum solution 10 “ 

Water 30 “ 

this being allowed to act for 30 or 40 seconds. 

For repeated printing one to two per cent, of gallic acid is 
added to the damping water. 

If the plate has been correctly treated the print or the photo- 
litho transfer will furnish many good impressions, but hardly 
equal to a stone. Further details as to the printing on the zinc 
plates, or the transfer of the chromated gelatine prints on to the 
same, will be found in Chapter IV. 

4 .—The greasy drawing materials which are necessary for 
lithography are litho tusch, autographic ink and fatty crayon. 

The two first are used in sticks and liquid form; the crayon 
is made in sticks only, and in that form is used more than the 
liquid in this country. The ink can be obtained in a liquid form, 
and the two others in solid state. All three materials consist 
principally of soap, tallow, wax, resin and soot. Soap and tal¬ 
low give the necessary grease, wax and resin give hardness and 
consistency, and soot the color. The proportion of grease in the 
drawing materials must be so great that even the finest lines or 
points of a drawing can be well transferred to the stone, so that 
they may not be attacked by the proper etching solution, and do 
not break away from the stone by continuous printing. As 
much black as possible in the drawing materials is pleasant for 
the draughtsman, but is not actually necessary for this particular 
purpose. 





































INTRODUCTION. 


7 


The tusch must dissolve well in distilled water and flow fine 
and clean from the pen. It should be tolerably brittle, and the 
fractured surfaces should be shiny. The photo-lithographer will 
frequently require the lithographic tusch for additions or for 


corrections. 

Yellow wax. 2 parts 

Mutton tallow . 2 “ 

Marseilles soap . 6 “ 

Shellac . 3 “ 

Lampblack . 1-2 “ 


These ingredients should be melted together by boiling. 

The autographic ink is, as a rule, used for drawing or writing 
on paper, and the result is then transferred to the stone. Instead 
of this, any litho tusch can be used, but for some work the auto¬ 
graphic ink is more advantageous. This ink must be thin, run 
easily, but not patchily, from the pen, and must keep for a long 
time equal in quality and action. It is very advantageous that 
specially prepared paper is not required, but the specially pre¬ 
pared autographic paper is much preferable, gives better results, 
and is cheap. The commercial inks generally possess these good 
qualities, and if much is not required one will hardly care to pre¬ 
pare it oneself. A good successful autographic ink which draws 
in brown may be obtained from the following formula:— 


Marseilles soap . 

. 10 

Tallow . 

. 10 

Shellac . 

. 12 

Yellow wax . 

. 12 

Mastic . 

. 5 

Asphalt . 

. 4 

Vine soot . 

. 3 

Distilled water . 

. 125 


Originals prepared with this ink transfer as well immediately 
as after several months, and ordinary well-sized writing paper 
can be used for drawing or writing on. 

Lithographic crayon is only prepared in the solid form for 
drawing on paper direct or on stone, according to the nature of 
the work, in three grades, hard, medium, and soft. The hard 
kinds, which are also usually leaner, contain more resin and less 
fat; the soft, on the contrary', more grease. 

Fatty crayon is composed of— 


Wax. 30 parts. 

Marseilles soap . 24 “ 

Tallow . 4 “ 

Shellac 1 part. 

Lampblack . 6 parts. 
































































8 


PHOTO-LITHOGRAPHY. 


Lean crayon is composed of— 


Wax. 12 parts. 

Marseilles soap . 8 

Tallow . 2 “ 

Shellac . 10 

Lampblack . 4 


For lithographic work a greasy ink is required in contradis¬ 
tinction to ordinary printing ink, which consists of linseed oil 
and lampblack, which would be called “lean.” For inking up a 
photo-lithographic chromated gelatine print such an ink cannot 
be used. In order to obtain a good result in transferring, this ink 
must contain grease, soap, and resin. 

Any good transfer ink can be used for a developing ink, as this 
is applied with a roller. It usually consists of equal parts of 
tallow, wax, soap, some resin, and as much litho ink as all the 
other ingredients put together. 

Many foreign inks are highly recommended, but the American 
Transfer Ink is quite equal, if not superior, to the foreign. It con¬ 
tains some asphalt and gum elemi, and works very well in 
practice. 

Thin developing inks, which are distributed with a broad 
brush or a pad, can be prepared by diluting good transfer ink 
with equal quantities of wax, benzine, and turpentine. 

A good developing ink must have the following properties: 
When spread upon the print must give a clean, sharp, sufficiently 
dense impression, which can be easily transferred to the plate or 
stone; on the other hand, the drawing ought not to spread. The 
transfer should possess such resistance that, without rolling up, 
it should resist a slight etching. 

5 .—The behavior of asphalt on stone or zinc. When a stone 
or plate is coated with asphalt solution and exposed under a nega¬ 
tive, and then washed with turpentine, the exposed parts remain 
insoluble, and in this way photo-lithographs can be prepared. 
The asphalt here takes the place of the fatty ink, and is, after 
printing, so firm and hard that without any rolling or inking up 
it can be etched with a weak, gummy, etching solution, which 
gives a cleaner, sharper drawing than the other processes. The 
asphalt and other light sensitive resins not only intimately com¬ 
bine with the stone or plate, but chemically alter the surface of the 
stone, and possibly in a more advantageous way than the greasy 
inks. When a properly exposed drawing on stone is, immediately 
after printing and development, treated for a long time with rec¬ 
tified or Neustadt turpentine, it is completely removed from the 
stone, and it will be found that the drawing appears of a somewhat 
lighter color than the rest of the surface of the stone. If this is 
now inked up with a roller, these places take up the ink without 
having previously come into contact with grease. Numerous ex¬ 
periments which I have made on various lines go to show that the 






















INTRODUCTION. 


9 


chemical theory of lithography has found an important enlarge* 
ment with the use of asphalt. 

The following are principal conclusions to he drawn from my 
experiments:— 

(a.) The exposed asphalt, whether this exposure is made by 
printing or whether a drawing is first made and then exposed 
to the light, adheres more firmly to the stone or zinc plate 
than if it was not exposed. An asphalt drawing prepared 
in the dark and inked up does not adhere to the stone, and this 
may be explained in that the grease cannot act through the 
asphalt film. Insensitive asphalt behaves in the same way. 
With correct exposure under a clear negative of about 20 degrees 
Vogel, and subsequent development and auxiliary exposure for 
about half to one hour, the drawing adheres firmly to the stone. If 
the image is to be washed off, the turpentine must act for five to ten 
minutes on the film, till the exposed asphalt has dissolved. If, after 
washing off, it is inked up, all the places take the ink well, and 
the image appears clear and plain. The image can only be 
destroyed by strong acids or alkalies, which actually dissolve the 
stone itself. 

From this it is clear that the prints neither require inking up 
nor strengthening in any other way, and my experiments have 
proved that in all cases the prints are, by this treatment, 
clogged up, and neither gain as regards a longer run nor in with¬ 
standing etching. 

( b.) Solution of asphalt, to which oil has not been added, behaves 
as described above; if, however, oil is added to it, it acts still 
better as regards the keeping of the drawing, and the prints need 
no subsequent exposure. Too large an addition of oil has the 
disadvantage that, in developing with turpentine, the asphalt 
dissolves too quickly. The images wash off and one hardly has 
time to examine. The exposed asphalt, to which oil has been 
added, also dissolves very readily. For the preparation of colour 
plates this point is of some importance. 

6.—The etching and preparing solutions are those solutions 
which make the stone suitable or unsuitable for taking the grease 
or water. Generally these are acids and gum arabic, either used 
alone or together. 

Of the acids the most important is nitric acid , the purpose of 
which is to convert the surface of the stone into a nitrate, so that 
the grease cannot penetrate. This acid acts even when diluted 
very energetically on the stone, and produces a fine grain. 

Hydrochloric acid exerts a less energetic action; it leaves the 
stone smoother and does not attack it so evenly as nitric acid, but 
has the same result finally. 

Sulphuric acid ought not to be used for etching stone. It forms 
calcium sulphate on the surface of the stone, and this separates 
from the stone in printing and spoils the pulls. 


10 


PH0T0-L1TH0G If A.PHT. 


Phosphoric acid may be used for etching as well as for preparing 
the stone; it exerts a very faint etching action and is seldom 
used for this purpose, but principally for making corrections. 

Acetic acid plays a very important part in lithography. It 
possesses the property, even in very dilute condition, of stopping 
the action of the gum and oxalic acid, and, indeed, even that of 
the stronger nitric, sulphuric, and hydrochloric acids. It finds, 
therefore, considerable use in negative printing, in making 
corrections, etc. It converts the stone into its original condition 
and makes it suitable again for taking ink. 

Citric acid fulfils the same purpose, but is, however, much 
higher in price. 

Oxalic acid is not used for etching, but only for preparation of 
the stone. By rubbing the stone with a solution of oxalic acid 
with a pad of cloth it takes a mirror-like surface or polish, into 
which the fatty ink cannot penetrate. It is used for preparing 
the stone for lithogravure, negative drawing, and negative 
transfer, etc. 

Tincture of galls , or instead of this, what is simpler, gallic acid, 
is used in lithography. It contains plenty of tannin, and is one of 
the most efficacious means of preventing the combination of the 
stone or zinc plate with fatty substances. 

Gum arabic or some other vegetable gum is indispensable for 
litho and zincography. A 10 per cent, solution of gum is generally 
used. It penetrates all the pores of the stone and the plate, and 
gives the same a thin but very firm fiim, and prevents the ink 
taking on these places. If it has become slightly acid it acts as a 
weak etcher, and as an addition to nitric acid it makes the same 
of thicker consistence and more easily distributable. The action 
of gum can be removed with acetic or citric acid; with water alone 
this cannot be perfectly effected. 

7.— Etching the stone. There are two principal etchings, the 
simple ordinary or first etching , which obviously has the purpose of 
giving the drawing the necessary stability and protecting the 
blank places from taking ink, and the deep or sharp etching gives for 
combination printing a still greater lasting power, and for large 
runs keeps the drawing clean and sharp. 

The ordinary etching chiefly causes the fatty substances to 
assume a new chemical condition, since in combination with the 
stone they form insoluble fatty salts of lime, which represent the 
printing surfaces. It has, however, also the property of cleaning 
the blank stone surfaces from any adherent grease, and makes the 
blank parts of the stone incapable of taking ink; also it makes the 
drawing clearer and more precise. 

The strength of the first etching may differ, according to the 
following circumstances:— 

(a.) The stone; for hard stones stand a stronger, and soft stones 
a weaker etching. 


INTRODUCTION. 


11 


(b.) The printing image ; fine drawings must at first he etched 
with a weaker solution ; coarser drawings, on the other hand, will 
stand a fairly strong etcher. 

(c.) The material with which the print or drawing has been 
prepared ; very fatty developing inks and asphalt stand well even 
with strong etching, whereas with lean or hard inks only a weak 
etching should be used. 

An etching solution which is at the limit of strength, but still 
suitable for a hard stone or a very coarse drawing, would 
irretrievably ruin a very fine drawing on a soft stone. 

Commercial acids differ considerably in strength, and it is, there¬ 
fore, better to use a hydrometer than a measure. It is also 
always more satisfactory not to nse the acid by itself, but in con¬ 
junction with gum. A solution of gum of eight to ten degrees 
strength is diluted with nitric acid till it measures 10 to 12 
degrees on the hydrometer. This solution may be safely used for 
every case, and it is only necessary to allow it to act longer for 
coarser drawings ; it should be evenly distributed over the surface 
of the stone with a clean soft pad. In very hot weather it acts 
more energetically, and then it should be used weaker for fine 
work. In any case it is advisable to let the stone or plate stand 
for some hours before etching, so that the ink may thoroughly 
combine. The etching of zinc plates will be more fully described 
later on; in other respects the treatment is the same as for stone. 

8.— Deep-etching process. The idea of this is chiefly to increase 
the printing form and to make the stone more resistant in printing. 
In working this the principal thing is to sufficiently protect the 
drawing from the action of the strong acid. This is generally 
done by dusting with resin, which has a low melting point. 

There are two deep-etcliiug processes which are chiefly used ; 
one in which the resin is melted with a spirit flame, the other in 
which the same thing is done by ether vapour. 

The procedure in each case is extremely simple. In the so- 
called burnt-etching process, which has been perfected by Eberle, 
of Vienna, the already etched stone ready for printing is rolled up 
w r ith a very stiff printing ink, not transfer ink, and then the 
drawing dusted with the finest powdered resin. The stone is then 
gone over with a cotton-wool pad and plenty of talc or French 
chalk, and then well dusted off with a broad camel’s hair brush in 
order to remove all traces of resin from the blank stone. To melt 
the resin a spirit lamp with a side flame is used. The flame is 
passed over the drawing, and ought only to be allowed to act 
sufficiently long to moke the resin combine with the ink, which can 
be recognized by the drawing looking shiny. If it has been 
melted too long the sharpness of the drawing is damaged. After 
this the etching may be at once proceeded with, and this is effected 
with a solution of gum to which 8 to 10 per cent, by measure of 
44 per cent, nitric acid has been added. For fine drawings 4 to 


12 


P.IOTO-LI l’HOGRAPHY. 


6 per cent, of acid should be used. In using this a fairly strong 
effervescence takes place, which should not frighten anyone. 

In the ether or cold-melting process exactly the same procedure 
takes place, only that instead of melting with an open flame this 
is effected by ether vapour. 

For this work a wooden stick of about 2 mm. thick is laid on 
two edges of the stone. On another ruler, which should be large 
enough to cover the whole of the stone, and which should be 
covered with flannel or stout cloth, ether is poured ; this ruler is 
laid on the others, so that it forms a right angle with them, and is 
slowly drawn over the surface of the stone. The ether vapour 
falls on to the surface of the stone and dissolves the resin which 
thus forms the protective film for the deep etching, which is done 
precisely as described above. 

Another melting process recommended by Scamoni consists in 
pouring alcohol on the stone and then setting fire to it. 

9 .—Differentiation of the printing processes. Technically we 
differentiate the principal printing methods into three, according 
to the method of production. The first and oldest is the typo¬ 
graphic or letterpress printing, which is founded on the principle 
that every line or every point w r hich ought to print must stand up 
on the plate, and all those places which must appear white in the 
print must be sunken in. The artistic effect is obtained by tones 
which are formed of individual lines or points, which are closer 
together or further apart, or else print finer or deeper. In print¬ 
ing a forme or plate, etc., it must be “ made ready,” that is to say, 
the pressure in printing must be so arranged for each part of the 
picture that on the lighter places or finer places less pressure 
must be exerted, whilst on the deeper tones more pressure should 
fall, according to their gradation. This balancing, w T hich is 
technically termed “ making ready,” is effected by cutting out the 
delicate and building up the strong or dark parts on the overlay 
With a proper overlay the artistic effect of the picture can be 
much increased; with a faulty overlay it can be quite spoilt. 
In letterpress printing the artistic element lies in the making 
ready. 

Typographic prints are distinguished by the lines, figures, etc., 
being somewhat pressed into the paper, and show raised up on 
the back, which is technically termed “impression.” When this 
“impression” is very plain, that is to say when the printing has 
gone pretty deeply into the paper, it is advisable before reproduc¬ 
tion to remove this by strong pressure. 

The second method of printing is exactly the opposite of the 
first, and is founded on the principle of printing from intaglio. 
The lines and points which should print are cut mechanically (by 
engraving or piercing) or chemically (by etching) into the stone. 
The etched or engraved intaglio plate represents a negative, or a 
reversed wood-cut, only with the difference that the lines do not 


INTRODUCTION. 


13 


lay in the same plane. In order to obtain an impression the ink 
is pressed into the cut-out parts, and is wiped off from the surface 
of the plate. By stronger or weaker wiping the print receives a 
stronger or weaker local tone, which is of great advantage from 
an artistic point of view, but which forms no small obstacle to the 
reproduction. 

The impression is represented in relief on the paper. Accord¬ 
ing to the depth of the lines they take more or less ink, and appear 
therefore raised up in the impression according to the amount of 
their depth in the plate. Reproduction photography has to 
reckon on this disadvantage, for with a side illumination the 
raised up lines cast shadows, and a correct negative does not 
follow. 

By the third method, lithography, of which we have already 
spoken, the impression lies generally flat on the paper like a draw¬ 
ing, if a very strong deep etching was not used, in which case it is 
also slightly raised. In printing from the graver or from stone etch¬ 
ing a faint relief is generally noticeable, which is never so high as 
with copperplate printing, and which is no important obstacle to 
making a photographic negative. 



CHAPTER I. 


1. General Notes on Photo-lithography. 

By photo-lithography we generally understand that process by 
which it is possible to prepare a printing plate or a stone by the 
aid of photography from any original, whether it be a drawing, a 
print, or an oil painting, either of the same size or smaller or 
larger than the original, which can be reproduced in the litho¬ 
graphic press. 

The main characteristic of this process is that either the 
original from which the reproduction is to he made must be pre¬ 
pared in distinct lines, strokes or points, or that any half-tone 
which may be present in the photographic negative must be 
broken up on the stone or plate into lines or points. 

The basis for the preparation of a photo-litho is as a rule a 
photographic negative on glass or gelatine, which, as the word 
negative implies, when examined by transmitted light, must have 
all its tones reversed, that is to say, the drawing or the lines, 
strokes or points which must in the print be black, must look 
transparent, whilst the other part of the negative which forms the 
groundwork must be covered or opaque. 

If every photo-lithographic process was to be described in detail 
there would be a great many, but actually they may all be 
classified according to two principal methods :—- 

(a.) One, in which the stone or plate is itself coated with the 
light sensitive substance and exposed under a reversed negative, 
so that a reversed image is formed on the stone or plate, which in 
printing comes in the right position, and 

( b .) The other, in which paper or a very thin zinc plate, pro¬ 
vided with a light sensitive film, is exposed under an ordinary, 
that is not reversed negative, and thus is rendered capable of 
receiving fatty ink, and is then transferred to the stone or plate 
by transfer. 

Of the many processes which, though differing in detail, may, 
looking to the final result, be assigned to one or other of the 
above-mentioned principles, there are two which have been 
especially tested in practice, namely, for the direct transfer , as we 
will call it, that process which is based on the light sensitiveness 
of asphalt or of an organic substance in combination with a 


16 


PHOTO-LITHOGRAPHY. 


chromium salt; and for the indirect transfer , that process which is 
founded on the light sensitive chromium salt in combination with 
gelatine, or briefly on the light sensitiveness of chromated gelatine. 
All other more or less complicated methods have disappeared from 
technical practice and have only the honour of being scientifically 
interesting and theoretically correct, but for various reasons are 
not practically valuable. 

It is indeed obvious that a discovery so important and useful 
to one of the principal departments of the graphic arts as litho¬ 
graphy is, and which may be called even more essentially capable 
of variation and multiplication, and perhaps in its way also more 
artistic, should call forth an earnest movement on behalf of the 
technical experts, principally with the endeavour for simpler forms 
and extension of its powers of work. This, indeed, has not always 
been attained, and these attempts will therefore only betaken into 
consideration in this book as may appear necessary, and all others 
will be passed over in silence. 

The methods used b^ some experimentalists for direct transfer, 
which consist in coating the stone with a solution of gelatine, 
albumen, or gum made light sensitive with a chromium salt, 
and after exposure under a positive or negative, obtaining a 
printing plate, were in execution complicated and troublesome, but 
in results fairly safe and satisfactory, so that they are now more 
and more used in practice. 

Iron and silver salts have been proved as not very suitable for 
photo-lithography, and at the present time for direct transfer 
asphalt is most generally used, and latterly also organic substances 
rendered light sensitive by a chromium salt ; for indirect transfer 
chromium salts in combination with gelatine, or chromated gelatine. 

Asphalt exposed to the action of light undergoes a chemical 
change which consists in its becoming less soluble in its original 
solvents. This was known to Nicephore Niepce, one of the dis¬ 
coverers of photography, whose endeavours to produce images by 
the action of light were actually based upon this very property of 
asphalt. He used for this purpose metal plates which were con¬ 
verted by a species of etching into printing plates. 

In the year 1852, the well-known Parisian lithographer 
Lemercier, in partnership with Lereboiirs, obtained a patent in 
Prance for a process by which they were in a position to obtain 
images on stone by the exposure of asphalt, and thus reproduce the 
same by printing in the ordinary way. They coated a lithographic 
stone with ethereal solution of asphalt, exposed it under a negative 
and developed it with ether ; there remained behind then the parts 
which had been rendered insoluble by light and formed a positive 
asphalt image on the stone, the outlines of which had the property 
of taking up greasy ink and with suitable preparation of giving an 
impression on paper. Such a stone was etched in the ordinary 
way with acid and gum, and then it was possible to make as many 


GENERAL NOTES ON PHOTO-LITHOGRAPHY. 


17 


pulls from it as was desired in litho ink. We have here a practical 
photo-lithographic asphalt process, as it is at the present time 
practised with various modifications, and which gave satisfactory 
results. 

Other resins besides asphalt may also be rendered sensitive to 
light, and it is well-known that they also may be used with as 
good results as asphalt for photo-lithography. 

That the good qualities of asphalt were even earlier recognized 
is proved by the fact that Negre, before the discovery of zinc 
etching, exposed a copper-plate coated with asphalt solution under 
a negative, washed out the places not affected by light, electro¬ 
plated these blank places in a gold bath, then cleaned the plate 
and deep etched it with acid. He obtained in this way an intaglio 
printing plate similar to an etching. 

By using a positive with this process a relief or typographic 
plate may be obtained, both of which processes are known as “ gold 
etching,” and were practised in the beginning of the ’50’s in the 
K. K. Hof-und Staatsdruckerei. 

The asphalt which is used for photo-lithographic purposes must 
possess certain qualities, of which the most important is as high 
a light sensitiveness as possible. With ordinary asphalt success 
will not be attained, since it is only slightly sensitive to light; the 
so-called Syrian asphalt is therefore generally used, which after 
having been prepared is dissolved in chloroform and then benzole 
and oil of lavender are added. 

Professor Husnik prepares an asphalt from which all constituents 
not sensitive to light have been extracted. Herr Yalenta produces 
his sulphurized asphalt. Both possess a far higher light sensitive¬ 
ness than ordinary Syrian asphalt, and are specially suitable for 
photo-lithography. 

The second, and considerably more extensively used method for 
photo-lithography—a transfer process—is based on the light sensi¬ 
tive property of the chromate salts in combination with gelatine, 
or albumen, or gum. 

That the bichromate salts possessed light sensitive properties, 
and could be used for photo-lithography, Mungo Ponton discovered 
in 1839. He printed on an ordinary paper, which had been 
rendered sensitive to light in a solution of potassium bichromate, 
drawings and silhouettes, and obtained after fixing, which was 
effected by merely washing in pure water, brown images on a white 
ground. 

Later Talbot found that the chromate salts in combination with 
organic substances under the action of light altered the property 
of the latter, and particularly that exposed chromated gelatine 
became insoluble in hot water. Poitevin used this discovery for 
carbon or pigment printing, and had produced in 1855 various 
pictures with this process. 

Poitevin discovered, further, that exposed chromated gelatine 

C 


18 


PHOTO -LITHOGRAPHY. 


would not swell up in cold water and took up greasy ink, and 
therefore after exposure under a photographic negative a picture 
could be obtained exactly inversely corresponding to the tones of 
the negative ; and that these places affected by light could be inked 
up and printed from, or could be transferred to a zinc or stone 
plate, and from this pulls could be prepared. By this discovery 
photo-lithography and collotype were actually discovered. 

Led on by his success, Poitevin used later, instead of gelatine, 
albumen and gum arabic, and prepared with these photo-litho¬ 
graphic prints, which were transferred to stone. 

If a solution of gelatine is mixed with a solution of bichromate 
of potash, and a sheet of paper coated with this mixture and ex¬ 
posed, or if the paper is first coated with gelatine and then bathed 
in a solution of bichromate of potash, various chemical changes 
take place as the result of the action of light on the gelatine film, 
which we will now consider. 

As has already been mentioned, glue or gelatine is insoluble, and 
only swells up in cold water. In warm water, however, the gela¬ 
tinous substance dissolves completely, and sets on cooling to a jelly. 
If a suitable sheet of paper is coated with the warm gelatine solu¬ 
tion, either by floating or pouring it over it, and it be allowed to set, 
and if this film is now made light sensitive in a solution of potas¬ 
sium bichromate and dried in the dark, we shall have a photo¬ 
lithographic paper which, according to the greater or less quantity 
of the chromium salt used, has a more or less intense yellow colour. 
If the paper thus prepared is exposed to light under a negative, or 
in another way if some places before exposure are protected by 
black ink or strips of paper, the places affected by light become 
dark coloured and brown, and at the same time they have lost 
their power of swelling up in cold water. The whole surface of 
the paper, that is to say the exposed and unexposed films before 
being laid in water, are flat or in one plane ; if, how r ever, the print 
is laid in cold water the exposed parts are not affected by the 
water, that is to say they have lost the property of swelling and 
remain in their original plane. The unexposed parts swell up and 
appear raised up on the print, and thus make the drawing sunken 
in. 

The exposed places have, however, now received the property of 
taking up and holding greasy ink, whilst the unexposed have taken 
up water and repel greasy printing ink. 

If the paper be exposed under a negative the drawing appears 
sunken in after development with water ; the other parts, which 
must in printing appear white, are raised up; by exposure under a 
positive the reverse is the case. 

If these prints are in any way, either by rolling up or brushing 
over, given a coating of greasy ink, the ink only adheres to the ex¬ 
posed places and a print in greasy ink is obtained, which, like any 
other greasy impression, can be transferred to a stone or a metal 


SUBJECTS WHICH CAN BE REPRODUCED. 


19 


plate, wliicli can be printed from direct, or the transfer may be 
made on to a metal plate for relief etching, that is to say for the 
preparation of a typographic block. 

In Poitevin’s process the stone itself was coated with a light sen¬ 
sitive chromated film, and exposed under a reversed negative. 
After developing and careful preliminary preparation of the stone 
the ink only adheres then to the places affected by light. 

This is also the case if the stone is coated with light sensitive 
asphalt, and the same printed on direct. After exposure the parts 
not affected by light can be washed off with turpentine, benzine, or 
linseed oil, so that the stone is laid bare ; the places, the parts of 
the drawing affected by light, however, are not dissolved. If the 
stone is now prepared with the solution of gum as has already 
been described, and then rolled up with an ink roller, these places 
will take the ink, and by etching, etc., the stone may be so pre¬ 
pared that the same may be printed from like any drawing or 
engraving. 

By photo-lithography only line or grained drawings can be re¬ 
produced, and half-tones, as is possible with collotype and photo¬ 
gravure, cannot be obtained. 

Now, with the aid of autotypic transfers and the asphalt process 
on grained stones, we have a perfectly satisfactory method of re¬ 
producing in an excellent manner half-tone drawings by the aid of 
photo-lithography. 

Photo-lithography in all its various branches of application is 
at the present time so perfected, and rests on so comparatively a 
simple principle, that a technical printer, with very little practice, 
experience, and observation of the formulae given, can attain in very 
short time absolutely good results. At the same time it must 
be said that frequently very great difficulties have to be con¬ 
tended with ; especially as regards the quality of the materials and 
negatives great care must be used. 

2. Subjects which can be Reproduced by Photo-Lithography. 

The next question which arises is, “ What can be reproduced or 
multiplied by means of photo-lithography F ” 

The answer is, “ According to the existing state of the technique 
of photography and the perfection of the transfer process, every¬ 
thing.” Any line or wash drawing, any oil painting or other 
plastic object, any photograph of living creatures or lifeless objects 
—briefly, any photograph can, under certain conditions, be trans¬ 
ferred to stone or a metal plate, and from this any number of 
impressions in greasy ink be obtained. Before the discovery 
of the method of breaking up half-tones into points or dots, only 
line drawings could be reproduced by photo-lithography. Since, 
however, it has been possible to break up half-tone into line or 
points or grain, nothing stands in the way of reproducing by this 


20 


PHOTO-LITHOGRAPHY. 


method any kind of original. This breaking up of the half-tone 
into a regular or irregular grain can be effected by means of a 
crossed line screen in making the negative, as in autotypic, or 
half-tone, block-making, or independently of the making of the 
negative, as in the asphalt process of Orell, Fiissli and Co., and in 
Barths’ process and various other methods. 

The undesirable half-tone must, however, always be broken up 
in some way into the requisite points or lines, as it is one of the 
characteristics of lithography that it is only possible to print from 
distinct figures on the stone. Lithography and letterpress print¬ 
ing produce impressions of sharply-defined lines or points, each of 
which must form a distinct whole. Any tone which is lighter or 
not absolutely black must be formed by lines or points standing 
in close proximity to one another. The tonality must be formed by 
stronger or weaker lines or points, by black and white spaces, or 
by more or less close line and point patterns. An absolutely closed 
tone, as in collotype or photogravure, is not attainable with 
lithography, and although numerous experiments have not been 
wanting to reach this end, the same have hitherto been without 
success. 

The half-tones are broken up and separated into solid printable 
points :— 

(a.) By the autotypic transfer, which is effected by placing ir 
front of the sensitive plate when making the exposure the above- 
mentioned crossed-line screen. 

( [b .) By the so-called asphalt process, by means of preliminary 
graining of the stone before coating with asphalt and printing. 

(c.) By means of the production of a grain on chromated 
gelatine. 

( d .) By the use of a sand blast, which is the chief point of 
Bartos’ process. 

(e.) By transfer of a close grating or network on to a polished 
stone, which forms the basis of the litho-lieliogravure process of 
General-Director Chas. Eckstein, which is included in photo¬ 
lithography. 

All these methods have for their purpose the breaking up of the 
light tones into regular or irregular but separate points. There 
are other methods besides those mentioned above which have the 
same purpose. 

We generally distinguish two kinds of reproduction:— 

(a.) Those from line drawings, in which a negative is made 
without the interposition of a cross-lined screen, and for which no 
other means is used for the production of a grain, and 

(6.) Those from wash-drawings, paintings, photographs from 
nature, etc., in which reproductions the half-tones are either 
broken up into lines or points by the use of the screen when 
making the negative, or by any of the other above-mentioned 
means after making the negative. 


LINE DRAWINGS. 


21 


(a.) Line Drawings. 

By the first method the drawing must be prepared according to 
certain formula if a good negative is to he obtained which shall 
not require much after work and disadvantages for photo-litho- 
grapby. A poor original may cause a partial or complete failure 
of the work, or at least cause much cost and waste of time; 
therefore it appears advisable to pay the necessary attention to 
the original which is to be reproduced. 

What a line drawing must possess which should be reproduced 
well by photo-lithography in order to give a good transfer on to 
stone we will now point out. 

Before all things should be noted that the paper must be pure 
white and smooth, yet not strongly reflective and not too weak. 
Smooth w T hite cards of medium thickness,are the best to use. 
Since all lines of the drawing appear in the impression of the 
same colour, there is not only no purpose, but it may even be very 
disadvantageous to the reproduction when the draughtsman, in 
order to increase the artistic effect of his work, or to produce good 
perspective, etc., draws fine lines or other points in a lighter 
colour. The striving of the artist for effect, perspective, etc., so 
far as this is attained by lines or parts of a lighter colour, has for 
this process of reproduction no advantage, but, indeed, the dis¬ 
advantage that by this the subsequent manipulations are rendered 
more difficult, the whole work will turn out more costly and finally 
less satisfactory. 

Although from the present position of photography drawings in 
any desired colour can be reproduced, yet it is most advantageous 
if the originals for photo-lithographic reproduction are drawn 
with fine black matt ink on smooth white papers, and the principal 
point to which attention should be directed is that all lines, even 
the finest, should be a good black, and should be kept of the same 
strength of colour as the other parts of the drawing. The thick 
lines "must be quite filled up like the shadow lines of a strong 
letter. Shading must be obtained by strong, fine running lines 
quite separate from one another. In this the single black lines 
must not be too strong, and the white spaces in between must not 
be too narrow, or otherwise when reduced in size the white 
interstices will disappear and will finally form a solid tone. The 
laying on of a tone or wash is not permissible, as even a light tone 
will appear in the reproduction as a black spot. It is not per¬ 
missible also to draw on the same original with inks of different 
blackness or consistency, and even if a coloured ink be used the 
whole original must be prepared with one colour (red, dark blue, 
green, or brown), and that as intense as possible. When we start 
from the only true standpoint, that every reproduction should be 
a reflex of the original as true as possible, artistic effects have from 
this point of view no purpose, since the printer in printing with 


9 . 9 . 


PHOTO-LITHOGRAPHY. 


one ink is not in a position to give grey lines as well as black, but 
can only give the appearance of everything in one colour only. He is, 
however, able to give with the strongest line the finest with their 
own characteristics, and can, therefore, in this direction attain the 
tonality of the original. 

It is obviously, therefore, the artist’s duty to draw in one colour, 
and since for photographic reproduction black is the best, that is 
to say Chinese ink, he will do well to completely lay on one side 
all other artistic materials or effects. At the same time it should 
be noted that originals drawn in any other colour can be repro¬ 
duced by photo-lithography, but if the drawing is to serve no other 
purpose than for reproduction it is best to prepare it in black. 

A further important requirement is that the drawing be sharply 
and cleanly worked, and since the reproduction of a ragged or 
broken line cannot make a full smooth beautifully running line, they 
will appear in the reproduction in the same defective way, and 
then require at least tedious retouching or make the printing of 
the subject actually impossible. If it is necessary to cross the 
lines in the shadows this must be done with great care. The 
points of crossing must be clean and sharp, and the ink must not 
run. Too close or too frequent crossing of the lines should be 
avoided, and would produce a bad and different effect in the 
reproduction. Smudges or wrinkles in the original appear in the 
reproduction more intense and more vigorous, and therefore it 
must not be forgotten to carefully avoid these, also any tracing 
lines must be erased, without, however, damaging the ink lines or 
rubbing up of the paper. 

Pencil and chalk drawings, assuming that they are cleanly 
executed, can be well reproduced by photo-lithography, only they 
ought not to be smudged or inked. Erasure marks on pencil 
drawings appear in the reproduction as smudgy spots. 

Drawings of architecture for illustration or other purposes, 
after consideration of these remarks, can be w r ell transferred with¬ 
out much trouble by photo-lithography on to stone or zinc. 

In drawings of maps, plans, etc., there are still some rules to be 
observed besides the above. Boundary lines or mountain ranges 
with fine hatching, waterlines for large rivers, seas or lakes, as 
well as the introduction of figures, are better left out of the 
drawing, and can be afterwards drawn on the stone; they will 
then be cleaner and sharper. If all these details, however, must 
be introduced into the original drawing, they should be executed 
in a pale blue colour, which will not appear in the ordinary 
negative. 

For plans with large letters it is better not to draw the latter, 
which are frequently a lot of trouble, but to employ the simpler 
plan of getting the titles, writing, legends, explanations, etc., 
printed by a book printer on paper of the same colour as the 
original, and stick them on the latter. The same method may be 


DRAWINGS ON BLUE PRINTS. 


23 


adopted when preparing railway, postal, and telegraphic charts or 
maps with a lot of names or other titles, etc. The network of 
lines may he drawn with litho ink as suggested above, but the 
names of the stations, etc., can be printed with letterpress and 
stuck on in the proper places. Working in this way not only will 
much labour be saved, but at the same time sharper and more 
correct titles be obtained on the reproduction. 

Any necessary instructions for carrying out the drawing should 
never be made on the paper with red pencil, but either with pale 
grey or pale blue. For this paper rubbed with indigo or graphite 
can be used or a scratched gelatine proof which has been i*ubbed 
with finely powdered milori blue. 

With commercial drawings it frequently happens that ornaments 
are repeated. It is not necessary for the designer to draw all the 
ornamentation, which may frequently be very complicated, if it 
runs over the whole of the design. It is quite sufficient, accord¬ 
ing to the size or the number of times that the ornament occurs, 
for the artist to draw it twice or three times, or sometimes ten to 
fifteen times ; the lithographer will duplicate it by transfer. This 
also applies if there is a border, or if there are any corner or 
centre pieces repeatedly used. It is quite sufficient to draw one- 
fourth of the frame or border, or with very complicated designs a 
complete corner, and to give the printer a rough sketch of the 
complete border. He will make the necessary impression on 
transfer paper by photo-litho transfer on the stone; he will also 
reverse the drawing from right to left, join up the different parts, 
and thus construct the whole border. This applies also to the 
corner and centre piece. 

(b.) Drawings on Blue Prints. 

As a substitute for a proof cyanotype or blue prints may be 
used for preparing drawings for photo-lithography and other 
graphic arts/ When a photo-lithograph like a pen and ink draw¬ 
ing is to be prepared from a coloured picture, or from a sepia or 
Indian ink wash drawing of a plastic object or a photograph 
from nature, or from an object not suitable for photographic 
reproduction an autotypic transfer is to be prepared, a proof of 
the desired object must be first prepared, and then from this the 
drawing is to be made. It is obvious that the proofs of the first- 
named can only be made in the original size, which under some 
circumstances may not be just what is required, assuming that 
the original can be used in this w T ay. In all cases this will be 
inconvenient and tedious, and possibly from the nature of the 
drawing many proofs be lost. The end will be attained far more 
quickly and safely if a negative is made of the original, either of 
the same size or enlarged according as may be desired. The 
negative thus obtained is used to make a ferro-prussiate print. 


24 


PHOTO-LITHOGRAPHY. 


For this we use a good firm drawing paper, which is sensitized in 
the following mixture :— 


Solution A. 

Potassium ferridcyanide 
Water 
Solution B. 

Amrnonio-citrate of iron 
W ater 


8 parts. 


150 




10 

100 


n 

n 


When dissolved each solution is filtered and mixed in the dark 
room immediately before use in equal parts. The solution thus 
formed is sensitive to light and is spread on a well-sized drawing 
paper as evenly as possible with a broad brush, equalized with a 
distributing brush, and then dried in the dark room. 

The coated side of the paper appears yellowish. It is then 
printed as usual until the deepest parts look grey, as the prints 
look weaker after developing. The prints are developed by 
floating them face downwards on a dish of pure water not too 
cold, and then washed till the drawing appears quite white on a 
blue ground. The washing must be thoroughly done or else the 
prints turn blue afterwards when exposed to light. These prints 
contain all the finest details, even in the deepest shadows, plainly 
visible, and will now be the most perfect and most convenient 
proofs for the artist. The tracing or drawing is now done with 
good black dull surface ink as already suggested. When the 
drawing is done it is allowed to dry thoroughly, which will be in 
from two to three hours. The following solution should be 
prepared: — 


Oxalic acid ... ... ... 1 part 

Water . 10 „ 

which should be poured into a flat dish and the drawing allowed 
to lie in it for about thirty minutes. It is then again well washed 
and then immersed for fifteen minutes in a bath of 


Hydrochloric acid ... ... 1 part 

Water . 20 „ 

The blue colour will now have disappeared, and the ink drawing 
will appear pure black on the white paper. It should be now 
hung up and dried in the ordinary way. This drawing prepared 
in wash or line with ink now forms the original for a furthei* 
photographic negative, which is made in the correct size of the 
reproduction with or without the intervention of the crossed 
screen according to the character of the drawing. With the 
negative thus obtained a photo-litho on stone or zinc, or a typo¬ 
graphic copper or collotype plate, or a photograph on wood for 
xylography may be prepared. 

The use of this process appears specially important for those 
cases in which an ordinary photographic negative is not sufficient. 


DRAWINGS ON PREPARED PAPERS. 


25 


for example where a printing plate cannot be prepared from the 
negative. It ought also to be useful when the light could not be 
controlled in making the negative, and thus incorrect effects 
appear in the reproduction, which often occurs in negatives from 
nature and with polished plastic metal objects. The enlarge¬ 
ments from the original are then used because the details can be 
better seen and the artistic character can be more easily seen. 
The fineness of the drawing must obviously be in proportion to 
the after reproduction, while tones may be partly or entirely lost. 

(c.) Drawings on Prepared Papers. 

For photo-litho transfer without the use of a screen there are 
some commercial papers, toned, grain, net or pyramid grained 
papers which may be used with excellent results. 

On these papers, according to their preparation, various 
excellent results can be obtained, which possess high claims as 
illustrations. 

A smooth white scratch board made by American and Euro¬ 
pean manufacturers, which has a very even film of chalk, and 
which takes the lines clean and vigorously, is especially suitable 
for pen and ink work. On this paper plucky drawings like wood 
cuts can be executed. The perfect white of the paper, combined 
with the vigorous black, facilitate reproduction with excellent 
results and without much trouble. 

An ordinary drawing pen and ordinary Chinese ink are used 
for drawing. The ink gives sufficiently black and matt lines. 

The deepest parts are covered with ink, and the desired shad¬ 
ing or stippling put in with the toothed scraper or engraving 
tool. The shading off of the shadows may also be worked up 
with the toothed scraper, and thus very delicate shading be 
obtained. 

Other very useful papers are known as stipple and white 
scratch board, with simple or double lines printed on them. 
These papers are also coated with a chalk film. 



Fig. 1. 


With these papers the printed lines or dots serve as half-tones 
for the artist, and by scraping with smooth or toothed scraper 
knives very many effects can be obtained. Lead pencil, chalk,, or 
litho ink can be used for drawing. For laying on, ordinary ink 
with a small addition of soap may be used. The new tone effects 












26 


PHOTO-LITHOGRAPHY. 


may also be produced with a half dry Chinese ink brush, but for 
any drawing for line reproduction washing with paler or darker 
inks is excluded. By scraping with the smooth scraper, points are 
formed in place of the lines, which by further scraping disappear 
entirely into white, by which means the transit into the highest 
lights is effected. If a black surface is scraped with the smooth 
knife a line tone is produced opposite to the printed one. By the 
aid of the toothed scraper, lines in any desired direction can be 
obtained. When the printed tone is only desired in parts of the 
picture, the other parts can be covered up with white paper. The 
paper is only stuck down by the edges with mouth glue; if it 
were stuck down all over with gum or starch it would be dis¬ 
torted. On the white paper stuck on, drawing may be done with 
the pen, and thus new effects again be obtained, as thus in a 
manner pen and wash drawing are combined. 

The white scraper boards without printed lines or dots are 
either impressed with a single line or with lines crossed at right 
angles. 

On this paper pen and ink drawings combined with grained 
tones may be done. The outlines and everything which is to be 
treated like a pen drawing may be done with a hard pen or a 
marten brush. Bright tones are so worked with the brush that 
smooth surfaces are not formed, but dotted darker or lighter 
tones. Those parts which have been laid on quite black can be 
brightened up afterwards with the smooth or toothed scraper 
knife or the needle, and thus many gradations obtained. Instead 
of the litho writing ink pastell or very black good litho crayon 
may be used for drawing. Obviously this paper should not be 
washed or smeared. 

The grain or stipple papers of various very successful manu¬ 
facturers are very suitable for drawings for photo-lithographic 
reproduction. The paper is coated with a chalk film of blinding 
whiteness, and is stamped with a regular grain of truncated 
pyramids, and is produced in numbers. 

This paper is drawn on with litho crayon or black pasted 
crayons. The deepest shadows are laid on quite black, and light 
effects are introduced with the scraper or engraving needle as 
with the above described papers. The same rules apply to the 
other parts of the drawing. 

For drawing in general or the use of effects in drawing it should 
be noted that with ad these papers the drawing may be somewhat 
overdone, and this is necessary in order to obtain the correspond¬ 
ing vigorous action in the reproduction. The printing ink is, as a 
rule, never such a deep black as the drawing ink, nor is the paper 
which is used for printing ever so white as the lines of the toned 
paper. The contrasts would, therefore, in printing become too 


REPRODUCTION OF PRINTS. 


27 


little, and flat unsatisfactory pictures would be obtained. With 
these drawings, therefore, the two opposites, “ black and white,” 
may be used to the extreme, even if the drawing is not satisfactory 
to the artistic eye. 

For making the drawing red paper ought not to be used, as 
when photographed red appears dark. Then blue proof paper, 
or paper rubbed with lead pencil, should be used. 

A drawing for photographic reproduction ought never to be 
rolled, and still less be folded; if it is to be sent away it should be 
packed flat. 

(d.) Reproduction of Prints. 

It is frequently required to make photo-lithographs of old 
prints As already mentioned in the introduction, we distinguish 
three different methods of printing, of which the two first, typo¬ 
graphy and lithography, are confined to the rendering of well- 
defined lines or points, whilst copper-plate printing can to a 
certain extent reproduce lines and tones. As regards the repro¬ 
duction of the first two, so far as their fundamental character 
goes, no insuperable difficulties present themselves, when they 
correspond at least to the general requirements of a drawing. 
Since a reproduction, with exceptions, can never be better—- 
obviously without very complicated retouching—but always some¬ 
what inferior to the original, the appearance of the original will 
always be some guide as to the quality of the reproduction that 
can be produced. 

If, however, prints are prepared specially for this purpose, the 
following points should be observed : — 

1. For printing a matt surface a so-called pure white chromo 
paper should be used. 

2. The ink should be black and of good body, the impression 
clean and sharp, every line exact and not in the least fuzzy. 

The expert lithographer will easily prepare his impression. 
Assuming that he has a good original stone, he will more easily 
make good and correct prints from the engraving from the chalk, 
pen or other drawing than the typographer. The latter has to 
give his impressions the correct finish by means of overlays, 
without the correct making and use of which no good picture, 
whether it be characters or a drawing, can be obtained actually on 
a typographic press. The reader is referred to my article in 
Professor Eder’s “ Jahrbuch fiir Photographie und Reproductions- 
verfahren ” for 1891, where I have treated of this at length. Prints 
produced by the third method, copper-plate printing, give far 
greater difficulties to the photo-mechanical worker. Every pull 
from the engraved plate—etching scraper drawing and photo¬ 
gravure excepted—possesses a tone on its surface, which is, more¬ 
over, very unequal, and although increasing its artistic qualities, 
offers, however, considerable difficulties for reproduction. This can 


28 


PHoTO-LIT HOGRA PHY. 


only be avoided by very troublesome retouching, which is fre¬ 
quently prejudicial to the beauty of the picture. 

If pulls are specially prepared for reproduction the copper-plate 
printer must very carefully polish his plate and print without a 
tone, but still this must not be done so that the plate is too strongly 
polished that the depths lose their vigour; this would give an 
absolutely incorrect picture as regards gradation of tone. 

Etchings can, as a rule, only be reproduced with the aid of a 
cross-grained screen, and the same applies to photogravures, 
although the latter will seldom be required. 

All tone or painted originals, such as wash or sepia drawings, 
photographs from nature, collotypes, photogravures, water-colours 
and oil-colours can only be reproduced by photo-lithography by 
the interposition of a screen when making the negative, or by a 
process in which the breaking of the tone is effected independently 
of the photographic negative, and which will be described later 
on. 

With old photographs which have faded it is as well to increase 
the lights and shadows by painting. 

(e.) Size of the Reproduction. 

A question frequently asked is, “ Of what size should a drawing 
be made in order to obtain a good photographic reproduction ? ” 
This question cannot be precisely answered, for a good deal 
depends upon the object itself, and on the kind of drawing. 

It may be generally said, however, particularly as regards pen 
and ink drawings on smooth paper, that they should never be 
smaller, only very rarely of the same size ; they should be drawn 
one-third or one-half larger generally. The artist can execute fine ' 
details more easily and precisely on a large drawing than on a 
small one. 

The enlarged reproduction gives any faults or mistakes which 
may happen to be in the drawing in proportionately larger size 
quite independent of the fact that an enlarged reproduction is 
always somewhat rough and ordinary. Reproduction in the same 
size reproduces the faults the same size as they exist in the draw¬ 
ing ; the reduction, however, also reduces the failings of the 
drawing if it cannot also absolutely remedy the same. The re¬ 
duced copy has always something finer and more delicate. The 
degree of reduction must be kept in mind, and the drawing be 
done with this in view. 

If a drawing is executed very finely and full of detail, and, 
besides that, contains very small lines of drawing or titles, they do 
not gain in reduction, but the opposite ; they lose, as much that in 
the drawing appears plain and distinguishable becomes by strong 
reduction indistinct and unrecognizable, or appears to the eye as a 
tone. 


SIZE OF THE REPRODUCTION. 


29 


Individual cases, in which for specimen purposes or to show how 
far reduction can go, many times linear, five, six, to ten times, 
cannot be taken into consideration, although the effect is usually 
well attained. 

It should also be observed that the drawing must be considered 
not only as regards its size, but also the strength of the lines and 
tones generally for reduction; this specially applies as regards the 
tones. By reduction the tone gradations are compressed, the pic¬ 
ture becomes poorer in tones, and although, theoretically con¬ 
sidered, light and shadow, that is to say black and white, are 
actually distributed in the same ratio as in the original, yet the 
reduced image appears proportionately darker and loses in artistic 
effect 

Great reductions will, however, be useful when for some special 
purpose such as the exact reproduction of geometrical figures or 
surface ornaments are required, as for instance in printing designs 
for cheques, bank notes, etc. In such cases the drawings should 
be made as large as is necessary for the most exact and easiest- 
carrying out of the figures, as in this way the precision of the 
drawing is better kept by reduction. In such cases, assuming that 
the ornaments are clear and open wdthout shading, the reduction 
may be carried beyond one-tenth linear. 

This kind of reproduction should present no difficulties either 
to the reproduction or printing. 

It is quite different, however, with drawings on scraper boards 
or grained paper. If it is kept in mind that with too great reduc¬ 
tion the gradations of tone of the print will be destroyed, and that 
in the same degree the difficulties of printing will be increased, 
care should be taken that reduction is not carried too far. When 
it is further considered that in a reproduction with 2,000 to 3,000 
points to the square centimetre the individual points disappear to 
the unaided eye, and the different thick layers of points appear as 
closed tones, the limit of reduction will soon be found. 

If we reckon according to this view, we can assume that those 
kinds of paper with coarse grain should be reduced at the 
most one-third, those with a finer grain a sixth, at the most a 
fourth, in order to obtain good printing plates which will give 
large editions. In this obviously will a good deal depend on the 
character and more or less rich in detail execution of the drawing. 
Still there are photo-lithographic processes such as the asphalt 
process of Orell Fiissli & Co., which contains about 15,000 points, 
and Bartos’ process, which contains 11,000 points to the square 
centimetre; still for reproduction in large quantities these pro¬ 
cesses offer many difficulties, and cannot therefore really be taken 
into account when considering this. 


30 


PHOTO-LITHOGRAPHY, 


CHAPTER II. 

THE PHOTOGRAPHIC PROCESS. 

1. The Studio. 

The arrangement of the reproduction studio is essentially different 
to that for ordinary portrait work. The general points of such 
arrangements are described in detail in the handbooks of Drs. 
Ederand Vogel, and these I may therefore omit so far as nothing 
novel is to be observed. 

We distinguish now between daylight and artificial light studios; 
further, those in which a camera is used for making the negative 
and those in which a dark-room itself is the camera. The first 
will, of course, be used where other things besides reproductions 
have to be made; the arrangement without a camera presents 
many advantages for reproduction work only. In the arrange¬ 
ment with artificial light the illumination of the object to be 
taken is effected as a rule with a source of light which can 
approximately replace daylight, and which also remains as con¬ 
stant as possible, and the electric light is at present the best. 
Although other sources of light are sometimes used, the electric 
light in the form of the arc light for continuous practical use has" 
the advantage. For copying oil paintings daylight is to be pre¬ 
ferred under all conditions, and for this the best arrangement is 
the revolving studio.* 

The description of a modern studio with electric light as used 
in the K.u.K. Militar-geographischen Institut in Vienna, and 
from which the studio of the K.K. Hof-und Staatsdruckerei was 
copied, is given here. This studio lies seven metres below the 
level of the street on the south front of the building, and is shown 
in Fig. 2. 

The preparation and dark rooms are illuminated with white, 
yellow, and red light by means of two 50-c.p. incandescent electric 
lamps for each colour, and besides this are provided with window 
screens of glass of the same colours for daylight. 

The windows open into an area 50 cm. wide which runs round 
the building The lighting is so arranged here that besides the 
ordinary collodion plates, very sensitive gelatine plates can be 
worked. The room C, where the original is placed, is fitted up 

* See Eder’s “ Jahrbuch fiir Photographie,” 1893, p. 231. 


THE STUDIO. 


81 


with four Franzenarc lamps of 3,000 c.p. each for illuminating the 
original, and the lamps are so arranged that the light falls 
centrally on the original. The four lamps are fastened by ball 



Fig. 8. 

A is the room for the preparation of the plates, for the wet collodion plates, and 
the silver bath. 

B the developing room. 

C is the room in which the original is placed, where is found a support for the 
original TT', as is shown in Pigs. 3 and 4. 

D is the dark-room with the focussingtableEE'(Figs. 2 and 3), and is separated 
from C by a wall of 15 cm. thickness. In this wall is found the photo¬ 
graphic lens in a metal flange built into a stout iron box. 

P is the washing and polishing room for the glass plates. 

and socket arms to an iron frame which rests on rollers ; they can 
be raised or lowered on the frame, and for taking small objects 
can be pushed closer together. The arms are fastened to the 
round pillars of the frame, being provided with a screw grip. 
The lamps can be placed as close as 05 m. to the original. As a 
rule, however, they are worked at a distance of one metre, as then 
the intensity of the light is about equal to diffused daylight. The 
axes of the carbons in the lamps are so arranged that the glowing 
crater formed in the positive pole is turned to the original, by 
which means the illumination is intensified. The positive carbons 
have a diameter of 20 mm., the negative carbons 8 mm. The 
lamps stand in pairs one above the other at LL'. In the two 
upper lamps the positive carbon is at the top and the negative 
carbon below it, so that the light is equally distributed over the 
whole of the subject. With this arrangement of the lamps all 
reflections are avoided, and neither the grain of rough drawing 
paper, the relief of an engraving, nor the edges of pieces stuck on 
are felt. The current is produced by a dynamo in the house ; it 
enters into the place at N, whence it is divided into two circuits of 
20 amperes, in which are two switches, an ammeter and a rheostat, 
and the two lamps on either side. 

The wall in which the objective O (Figs. 3 and 4) is placed, as 
also the brick socle aa and ee (Fig. 2), on which the support for 




















32 


PHOTO-LITHOGRAPHY 



I 

















































































THE STUDIO. 


33 



D 

































































































































34 


PHOTO-LITHOGRAPHY. 


the original and the focussing screen rest, run on rails, and 
are absolutely isolated from the brickwork of the building m order 
to avoid any possible vibrations. 

The stand for the original TT' is provided with screw fittings, 
cams and wheels, which make it possible to raise the original, to 
lower it, to move from right to left, and vice-versa !, vertically and 
horizontally, so as to place its centre axial with the optical axis of 
the lens, as well as parallel to the focussing screen in the dark 
room. The whole of the mechanism lies at the back of the stand, 
so that there is absolutely nothing in front of the original. 

The focussing table BE' is constructed in a similar manner to 
the stand for the original, and is movable in every direction in 
the same way. It carries in front two wood clips, in which the 
board with the original is placed. The table for the original, 
like the focussing table, is constructed on rollers, which run on 
the already-mentioned rails. In order to be able to fix these as 
soon as a sharp focus is obtained a brake is fitted. The placing of 
the original table at the distance from the lens is accommodated 
according to the size in which it is to be reproduced, and has 
already been estimated. There remains, therefore, only to trouble 
about the fine focussing, which is very quickly effected. 

For taking line or wash drawings and for enlargements up to 
80 x 80 cm. a Steinheil wide-angle aplanat is used, which gives no 
distortion. The duration of exposure is with such subjects from 
eight to ten minutes. For smaller subjects, and principally for 
photographs on wood, an orthoscope by Voightliinder is used* and 
the exposure varies from four to six minutes. 

A Zeiss anastigmat is used for making autotypes. Duration of 
exposure from three to five minutes. Coloured objects, oil paint-" 
ings, etc., are taken in the daylight studio. They are printed in 
the daytime in the open air, and in bad weather or under pressing 
circumstances in the night by the electric light. 

2. The General Qualities of Negatives for Photo-lithography. 

The negative for photo-lithographic work, for whatever method 
it may be used, must before all things possess two principal 
qualities ; when looked through it should be as clear and as clean 
as possible, on the other hand the ground as well covered as 
possible. The deposit must not be of a black colour; from a well- 
drawn original absolutely satisfactory negatives can be prepared 
without the black colour. When a drawing is reduced which 
contains grey lines, dots, and points, as well as full black ones, 
toned lines will be visible as well as the transparent; with careful 
treatment, the negative may be so far corrected that it may be 
used. If this is not effected, or is not possible, the retouching 
on the stone will be somewhat troublesome. The toned lines print 
later than the transparent; these will therefore be overprinted 


THE GENERAL QUALITIES OP NEGATIVES. 


35 


when the former have scarcely reached the correct degree of 
printing. The choice is then only left either to weaken the Hues 
which are too strong or to draw afterwards the faint or not 
printed lines. 

If the ground is not sufficiently opaque it will print through. 
This can be remedied by intensifying the negative, or when this 
is not possible to paint over it as well as possible. 

Transparent spots are formed on the negative by an impure 
silver bath or by dust flying about the room. These must be 
spotted out if increased work later on on the stone or zinc plate is 
not desired. 

In reproducing fine copper engravings, it generally happens 
that the fine grey hair-like lines and the light interstices, if the 
plate was not properly polished, appear less transparent in the 
negative than the other parts of the picture. In developing the 
print the result is a partly broken image which can only be re¬ 
touched with considerable trouble. The negative can be corrected 
by taking care to paint over the transparent parts. Professor 
Husnik recommends, when the picture is not too large, to fasten a 
transparent paper on the back of the negative, and to cover over 
the glassy places with a soft lead pencil. These parts then print 
simultaneously wfith the hair-like line and develop also equally. 
If, however, the negative is large, and the picture very complicated, 
a glass positive picture is prepared in the following manner: A 
polished sheet of glass is levelled and coated with the following 
solution :— 


Gelatine 

Sugar 

Ammonium bichromate 
Water 


6 parts by weight. 
1 part „ 

1 >» 

80 parts „ 


When the solution has dried the glass plate is laid on the 
negative and exposed till the deepest shadows have printed, and 
it is then developed in water. When dry this glass positive is 
laid on the back of the negative so that every part of each picture 
fits. The plates are then bound round the edges with paper 
strips so that they cannot shift. By this —although somewhat 
troublesome—operation can an unsatisfactory negative be 
rendered more even. 

This correction can also be effected in the following manner: 
The back of the negative is coated with raw collodion which 
is faintly coloured with aniline red, eosine or fuchsine, allowed 
to dry, and then with an engraving needle or a narrow knife 
the less transparent lines may be scraped out, so that the red 
collodion only remains on the transparent places. Obviously 
also this can be done in the reverse, by painting a faint red 
on the transparent places with a brush. 

By this last method a tolerably extensive retouching may be 


36 


PHOTO-LITHOGRAPHY. 


effected on unequal negatives, which, are the result of not quite 
equally black or also very close drawn originals, from subjects 
with very fine lines, such as copper-plate engravings, or from 
finely-executed lithographs with very great reduction. Finally 
it should be mentioned that with intelligent retouching any bad 
negative can be used for photo-lithography, and the only question 
now is whether it is not better to take the shortest way and 
prepare a suitable negative when the original really permits of 
its being done. In printing on chromated gelatine paper a good 
result can be easier attained from somewhat foggy or thin 
negatives than by printing with asphalt or other light sensitive 
substance. 

The following kinds of negatives are used for the various 
photo-lithographic processes : — 

For the transfer process with chromated gelatine paper or 
direct printing on stone or zinc direct, a reversed line or autotype 
negati ve. 

For Orell and Fiissli’s process, a reversed ordinary half-tone 
negative. 

For Bartos’ process and for photogravure on stone, a direct 
ordinary half-tone negative. 

3. Preparation op the Direct Glass Negative. 

The preparation and cleaning of the plate glass is as follows :— 
First of all the plates are roughened with a piece of sharp pumice 
stone on the extreme edges to the breadth of about 0’5 cm. in 
order to prevent the frilling or floating off of the collodion film. % 
This is very little trouble considering the advantage it offers. 
After being edged the plates are placed in a solution of 
Nitric acid chemically pure ... 1 part 

Water ... ... ... ... 10 parts 

Instead of nitric acid, chromic acid may be used, but this is not 
absolutely necessary. 

After one or two hours the plates are taken out of the acid 
bath, well washed under a strong water rose, and dried in a 
place free from dust. Then the plates are well rubbed with 
1:10 tincture of iodine solution with a pad of clean filter paper 
and then polished with 50 per cent, alcohol. This preparation 
must be done with absolute accuracy, and thus they make all 
substrata of albumen, india-rubber solution, etc., for direct 
negatives unnecessary. 

Plates which have been previously used are placed in pure 
water till the collodion film has become loose, and are then 
scrubbed with a stiff brush, treated for some hours to a bath of 
caustic soda, and then treated as above, when they may be used 
again. 


PREPARATION OF THE DIRECT GLASS NEGATIVE. 


37 


For reproduction of simple line drawings iodized collodion is 
used which consists of 2 per cent, raw collodion composed of— 
Ether ... ... ... ... 1,000 ccm. 

Absolute alcohol... ... ... 1,000 „ 

Pyroxylin ... ... ... 40 g. 

Iodizing is done with 


Sodium iodide 
Cadmium „ 

„ bromide... 
Potassium iodide 


15 

15 

8 

1 


>> 


The last salt is dissolved in a few drops of distilled water, the 
other salts are dissolved in one part of the absolute alcohol. 
The iodizing solution is filtered into the raw collodion, which 
has already been allowed to settle and filtered, and allowed to 
stand for some days. 

The sensitizing solution is nitrate of silver in the proportion 
of 1:10, with larger sizes 1 to 12 — 1 to 14, and the silver bath 
is faintly acidulated with chemically pure nitric acid. 

For a monochrome subject the exposure lasts according to the 
size of the reproduction, and the rapidity of the objective, from 
three to ten minutes. 

For development an iron developer is used, consisting of :— 


Water... 

Ferrous sulphate 
Copper sulphate 
Alcohol (40 per cent.) 
Glacial acetic acid 


4000 ccm. 
150 g. 

75 „ 
250 ccm. 
125 „ 


The iron developer, with addition of sulphate of copper, is to 
be preferred for short exposures to iron and lead developer. If 
the plate has been correctly exposed the image gradually appears 
after a short time, and very soon gets vigorous. When the details 
appear in the deepest shadows the development must be immedi¬ 
ately stopped, otherwise fogging will ensue. If the image does 
not gam vigour by long development it was under-exposed ; with 
over-exposure the image appears quickly and remains thin. The 
developer, when fresh, works fairly quickly; older developers 
work slower, but give very clear negatives. 

For very fine line drawings or reproductions of copper-plate 
engravings the developer is used somewhat weaker, and one-fifth 
of its volume of water added. The development takes somewhat 
longer; the fine lines remain, however, very clear. 

After developing the plate is well washed and then intensified 
first with a solution of — 

Water. . 5000 ccm. 

Ferrous sulphate * ... ... ... 180 g. 

Citric acid ... ... ... ... 90 ,, 



38 


PHOTO-LITHOGRAPHY. 


to which a few drops of a 1:12 silver nitrate solution have been 
added. Care should be taken that in the first intensification 
the glassy places remain clear. When, therefore, the desired 
opacity is attained the plate should be immediately washed. Too 
long intensification fogs the finer lines. 

The plate should be fixed with 5 per cent, solution of potassium 
cyanide. For this, however, a concentrated solution of hypo¬ 
sulphite of soda can be used. 

After well washing, the negative will show, when examined by 
transmitted light, w r hether the ground is opaque enough, or 
whether a further intensification is necessary. With correct 
manipulation this first intensification will be sufficient for fine, 
well-prepared drawings. 

If, however, the opacity proves to be too little, after thoroughly 
well washing, the second intensification or blackening is effected 
with a concentrated solution of mercuric chloride in distilled 
water, which is allowed to act till there is a distinct precipitate 
and the film has become grey. After well washing the plate is 
flowed over with solution of thiosulphate of gold till the grey 
quicksilver precipitate has become absolutely black. The gold 
solution consists of — 


(A.) Distilled water 
Chloride of gold 
(B.) Distilled water 

Hvpo-sulphite of soda 


... 1000 parts 
... 1 part 

... 1000 parts 
... 10 „ 


Immediately before use solution A is added with constant 
stirring to solution B, and a few drops of ammonia added. If 
the desired blackening is not effected with one application the , 
operation must be completed. 

The solution of gold, when kept in the dark, wiU keep a long 
time. 

For fixed negative the following intensifiers have been used with 
good results :— 

1. Intensifier with pyrogallol. 


(a.) Silver nitrate... 

Distilled water 

... 5 parts by weight 

... 75 „ ,, 

To this solution is added — 


(6.) Citric acid 

Distilled water 

... 5 parts by weight 

••• 75 „ ,, 

(c.) Pyrogallol 

... 125 „ 

Distilled water 

... 150 „ 

2. The hydrochinone intensifier recommended by Baron Hiibl:-- 

Hydrochinone 

... 10 parts 

Water... 

... 1000 „ 

To this as much acid is added as 

will keep the solution clear for 


PREPARATION OF THE DIRECT GLAS3 NEGATIVE. 


33 


five minutes, when it is mixed witli a third of its quantity of 1 :30 
solution of silver nitrate. The addition of a few drops of sulphuric 
acid or 5 parts of citric acid is generally enough. This intensifier 
acts somewhat more delicately than the silver and iron solution, 
and has the advantage over the pyrogallol that it can be applied as 
frequently as desired in full daylight to the fixed negatives with¬ 
out any danger. 

3. The metol intensifier. 

The negative should be developed with the above-mentioned 
iron solution:— 


(A.) Metol. 


... 

... 15. parts 

Citric acid 

• •• 


... 10 „ 

Distilled water 

• • • 


... 1000 „ 

(B.) Silver nitrate... 

tti 


... 10 „ 

Distilled water 

... 


... 100 „ 


The negative must be fixed before intensification with hypo and 
well washed. 

A small quantity of solution A is poured over the negative to 
drive off the water, and then it is intensified in the ordinary way 
with 10 parts of solution A and 1 part of solution B. 

Further intensification is effected, as described, with mercury, 
the blackening with thiosulphate of gold. 

When the negative is finished and dried it is coated with a 
solution of gelatine 1 : 50, or a 1 :15 solution of gum, in order to 
protect the film, and the negative should be levelled and allowed 
to dry. 

Good opacity in the ground and clear glass in the lines of the 
drawing are the fundamental requirements of a negative for photo¬ 
lithography. But drawings are not always prepared in such a 
manner that this can be completely obtained. With flat drawings 
which are drawn in grey instead of black the first intensification 
is only continued till the finest lines appear clear. For further 
intensification the negative after drying is given a coating of a 
light sensitive solution of— 


Gum arabic ... 
White sugar ... 
Potassium bichromate 
Glycerine 

Water ... . 


.. 17.5 parts by weight 


.. 17-5 


55 


55 


.. 5*8 
.. 1-8 
.. 35 


55 

55 

55 


55 

55 

55 


Ammonia is now added till a light colour is formed. After 
drying it is exposed from the glass side to 15° Vogel’s photometer, 
washed for about a quarter of an hour and then soaked in warm 
water till a relief is formed. By this operation a transparent relief 
is formed on the lines of the drawing, which absolutely protects 
the same from fogging. The intensification is then effected with 
mercuric chloride and chloride of gold, or an intensifier of solu- 










40 


PHOTO-LITHOGRAPHY. 


tions of uranium and ferridcyanide is used, which is composed 
two solutions — 


(A.) Uranium nitrate 
Sugar ... 

Water ... 

(B.) Potassium ferridcyanide 
Sugar ... 

Water ... 


... 8 parts by weight 

... 8 „ 

... 350 ,, „ 

8 parts by weight 
8 „ „ 

... 350 ,, ,, 


of 


The negative is first flooded with the uranium solution and then 
with the red prussiate. 

Another process of intensification recommended by. Prof. Eder 
and Toth is the so-called lead intensifier. 

The somewhat under-exposed negative ought only to be 
developed with iron, fixed with hypo, and must then be well 
washed. It is finally well rinsed with distilled water, and then 
placed in a filtered solution of— 

Lead nitrate ... ... ... 4 parts by weight 

Potassium ferridcvanide ... 6 „ „ 

Distilled water ... ... 100 „ „ 


After a few minutes it becomes absolutely opaque in the covered 
parts. The negative is allowed to remain in the bath till it has 
attained the desired density. On the silver molecules of the 
image a pale yellow precipitate has formed by the action of the 
lead bath. The ferridcyanide of potash is reduced by the silver 
to yellow ferrocyanide of potash, and gives then, with the lead 
salt, an insoluble compound, ferrocyanide of lead. By the action 
of ammonium sulphide the unstable lead salt is converted into a, 
stable salt. 

As soon as the negative has been taken from the lead bath and 
well washed, till the washing water no longer gives a blue pre¬ 
cipitate, it is flowed over with dilute ammonium sulphide 1:5. 
Sodium sulphydrate may also be used. The image becomes black 
instantaneously. The negative becomes generally vigorous ; if, 
however, it was exposed too long the fine hair lines and points veil 
over very easily. 

If the negative is not sufficiently intensified, which may happen 
with very much under-exposed negatives, it should after well 
washing, and before treating with ammonium sulphydrate, be 
laid in a bath of— . . 

Cadmium sulphate... ... ... 10 parts 

Distilled water ... ... ... 100 „ 

in which it becomes still whiter, and should then be treated with 
the ammonium sulphide. The lead, the cadmium, and the silver 
of the bath are converted by the ammonium sulphydrate into 
sulphide. The negatives treated with cadmium have a yellowish 
tinge, whilst those treated with lead are pure black. For clear- 


PREPARATION OP AUTOTYPE NEGATIVES. 


41 


ing up the white-lead image when it is too vigorous or is foggy 
hyposulphite of soda or a dilute solution of potassium cyanide can 
be used. This manipulation, however, requires great care. The 
negative treated with ammonium sulphide if foggy can be cleared 
up with hydrochloric acid, used weak and repeatedly poured on 
and off, with careful watching of the action. After this it must 
be well washed. 

The lead solution will remain clear for weeks, and if it begins 
to work slowly can be freshened up with addition of lead nitrate 
and ferridcyanide of potash. 

If stripping negatives are to be prepared, it is advisable, w r ith 
the lead intensified negatives, to give the glass plate a preliminary 
rub with vaseline oil, to well wash, and then to coat with raw 
collodion. 

Husnik’s graphite intensification is still to be mentioned, which, 
in some cases, may be of great service, but requires practice and 
care. 

The expert photo-mechanical worker will adopt one or the other 
methods for his work, and as soon as he can work safely and with¬ 
out hesitation he will adhere to that. 


4. Tee Preparation op Autotype Negatives of Black and 
Coloured Drawings. 


As regards the preparation of antetype negatives from simple 
black originals—wash drawings—the above photographic pro¬ 
cesses are quite sufficient. For taking painted originals—such as 
oil paintings, water-colour drawings, fresco, and pastell draw¬ 
ings—an orthocliromatic collodion must be used if a correct 
rendering of the tones in the negativeis to be obtained. 

In our studio we have obtained excellent results with two 
kinds of colour sensitive collodion. These are the isochromatic 
collodion emulsion prepared by Dr. E. Albert and that suggested 
by Major von Hiibl. In using the former, the glass plates as soon 
as they are taken out of the acid bath and well washed must be 
given a substratum of the following solution :— 

White gelatine ... ... ... 5 parts 

Water. 500 „ 


to which is added— 

Glacial acetic acid .. ... ... 15 parts 

Alcohol ... ... ... ••• 10 „ 

The solution should be filtered and coated whilst warm, and the 
plate dried in a room free from dust at least 15° It. 

For the production of the sensitiveness, or for the production 
of the correct reproduction of the colours, two eoside of silver dyes, 
R. and P., are used. The P. dye gives great sensitiveness, and is 
especially suitable for portraits, landscapes, etc. In using this a 


42 


P HOTO- LIT riOGRAPH Y. 


correct reproduction of the red must be abandoned, whilst the It 
dye gives an absolutely correct colour rendering but requires 
about double the exposure Ten ccui. of the eoside of silver 
solution are added to 100 ccm. of the emulsion. When coloured 
the emulsion will only keep for one or twe days. 

The time of exposure with the ft. dye is normally from one-and- 
a-half to three minutes. 

After exposure the plate must be well washed under a tap and 
then allowed to thoroughly drain, or otherwise developing streaks 
will show. 

Hydrochinone developer is used for developing, consisting of 
three solutions :— 


(A.) Distilled water 

... 500 parts 

Sodium sulphite 

... 200 „ 

Potassium carbonate (pure) 

... 200 „ 

(B.) Hydrochinone 

... 25 „ 

Alcohol (96 %) . 

... 100 „ 

(C.) Ammonium bromide 

... 25 „ 

Distilled water 

... 100 „ 


This developing liquid is concentrated, and is used as follows:— 


Solution A. ... 



100 parts 


5 

7 


5 ) 


To obtain hard negatives solution B is increased from 1 to 5 
times. A mixture of 150 parts of the above solution with 1000 
parts of distilled water forms the actual developer. By the addi¬ 
tion of more concentrated developer or increasing the quantity of 
water the developer may be suited to the character of the subjects 
The developer must be freely flowed over the plate, and then the 
plate fixed with sodium hyposulphite. Intensification is effected 
with— 


(A.) Pyrogallol . 

Citric acid ... 
Distilled water 
and when dissolved 

Glacial acetic acid ... 
are added. 

(B.) Silver nitrate 
Distilled water 


1500 ccm. 
25 drops 

10 g. 

100 ccm. 


Immediately before use 100 parts of solution A are mixed with 
5 parts of solution B, and the intensification continued till the 
desired density is obtained. Negatives can be reduced by placing 
them whilst damp in a solution of— 


Potassium permanganate ... ... 1 part 

Distilled water . 300 parts 

When this has acted sufficiently, the plate is well washed, 



PREPARATION OF AUTOTYPE NEGATIVES. 


43 


flowed over with a five per cent, solution of potassium cyanide, and 
then well washed. When the dyed emulsion is used this must he 
done, after developing, in red light. 

A very excellent method of preparing an orthochromatic 
collodion emulsion has been described by Hiibl,* which can be used 
either wet or dry. Repeated trials made in the Imperial Military 
Geographical Institute, in our establishment, and in the Photo¬ 
graphic Institute in Vienna have proved the advantageous use of 
this method for orthochromatic work. The raw emulsion, ac¬ 
cording to Hiibl, is prepared as follows:—40 g. of silver nitrate 
are dissolved in 50 ccm. of warm distilled water, and as much 
ammonia added as will give a clear solution; then 100 ccm. of 
alcohol are added and the whole allowed to cool. 30 g. of 
ammonium bromide are dissolved in 35 ccm. of water and 70 ccm. 
of absolute alcohol with gentle heat. 

To make the emulsion 450 ccm. of four per cent, raw collodion 
are placed in a strong glass flask which will hold a litre, and to 
this in the dark room the silver solution added. Some of the 
wool separates out, but by vigorous shaking this can again be 
dissolved. A part of the silver salt also remains suspended in the 
liquid in the form of fine crystals. The ammonium bromide is 
added in three or four parts whilst warm. After shaking 
thoroughly for several minutes the emulsion is precipitated by 
distilled water, which is repeatedly added till the separation is 
complete. The emulsion, which is now powdery, is placed on a 
linen filter, washed several times with distilled water, squeezed to 
press out the last of the water, damped two or three times with 
alcohol, and then pressed. Whilst still damp with alcohol the 
emulsion is dissolved in from 800 to 1,000 ccm. of alcohol and 
ether, mixed with 0‘5 grs. of codeine, and allowed to rest for some 
days, when it will be ready for use. 

The preparation of the eoside of silver solution is effected as 
follows:—10 g. of yellow-shade eosine are dissolved in 250 ccm. 
of boiling water and 5 grs. of silver nitrate in 50 ccm. of water 
added hot. The solution is allowed to settle, then filtered, and 
then washed first with boiling water and then with alcohol on the 
filter, and then dried in a dimly-lighted room. 

To prepare the dye solution 0'5 g. of the dry eoside of silver and 
1 g. of ammonium acetate are gently heated together in 30 ccm. 
of alcohol till dissolved, then 120 ccm. of alcohol and 10 ccm. of 
glacial acetic acid are added, and the whole filtered. For plates 
to be exposed wet, 5-10 ccm. of glycerine are added. The emul¬ 
sion is sensitized by adding one-tenth of its volume of dye, and 
should be well shaken before coating the plates. The glass plates 
should receive a preliminary substratum of gelatine or india- 
rubber, so that the frilling of the film and impurities of the glass 
plates may be totally avoided. 

* “ Encyclopsedie der Photographie,” Heft 3, and Eder’s “Jahrbuch/’ 
1892, p. 387. 


44 


PHOTO-LITHOGRAPHY. 


For small sized plates the emulsion is used somewhat thicker 
than for larger, and for the latter it should be diluted with alcohol 
and ether. After coating they should be dried at about 15° C., and 
then for some minutes exposed to a temperature of 30° 0. 

The plates should be developed with the following mixture:— 
25 g. of sodium sulphite should be dissolved in 40 ccm. of warm 
water, then 10 g. of glycine added and 50 g. of potassium car¬ 
bonate, at first in small quantities in consequence of the evolu¬ 
tion of carbonic acid. When cool about 75 ccm. of a thin pasty 
liquid will be obtained, which may be kept as a stock solution, 
and before use must be well shaken and diluted with from 12-15 
times the quantity of water. Wet plates should be washed before 
development, and the developer flowed on ; dry plates should not 
be washed, and should be developed in a dish. 

They should be fixed in sodium hyposulphite. The intensifica¬ 
tion may be effected with metol (see p. 39), and the blackening as 
described on p. 38. 

Obviously the collodion emulsion may be used for ordinary 
work undyed. 

The qualities of the cross-lined screen and the distance of the 
same from the sensitive plate will be described in Chapter V. 

5. Preparation op "Reversed Negatives. 

For the different photo-lithographic work direct and reversed 
negatives are used; for the transfer process direct negatives are 
used; for printing direct on to the stone or plate, reversed nega¬ 
tives. 

For making the latter various methods are used, the principal 
of which are as follows : — 

(a.) Exposure through a Prism. 

This method is, on account of its inconveniences and difficulties, 
only used when it cannot be possibly avoided. 



Jig. 6. 



































































STRIPPING NEGATIVES. 


45 


Fig. 5 shows the arrangement in which the prism a is placed in 
front of the lens b. The prism is three-cornered and the angle 
turned to the objective is a right angle. The hypothenuse is 
silvered. It is mounted in brass or nickel; on the mount is a 
screw, by means of which it is fastened to the objective, so that 
the side opposite to the hypothenuse lies upright to the side of the 
camera, and this position must be an exact right angle to the 
focussing screen. The camera itself must be absolutely horizontal. 
The subject to be taken, instead of being in front of the camera, 
is placed sideways to the prism. The image passes through a', 
falls on the silvered hypothenuse a", from there through the 
objective b, through the box-shaped extension c and the camera d , 
on to the sensitive plate, which is not visible in the diagram. 
The exposure with the prism is about gth longer than usual, 
because a portion of the light is absorbed by the prism. 

(b.) Placing the Plate the Wrong Way Roond in the Slide. 

Generally, for making reversed negatives of line drawings, it is 
quite sufficient to place the sensitive plate the wrong way round 
in the dark slide or in the carrier, so that the film side, instead of 
being towards the objective, is turned towards the operator. It 

is, of course, absolutely essential to use only glass plates which 
are absolutely clean and which contain no particles of sand, air 
bubbles, etc., which would show on the prepared negative as 
points. After sensitizing the plate, the back of it must be 
thoroughly cleaned, for any smudges or drops would be visible on 
the negative. Obviously great care should be taken also in 
cleaning the plate to make as little dust as possible. In the 
Imperial and State Printing Works nearly all the reversed 
negatives are prepared most satisfactorily in this way. 

The photographic manipulations, the preparation, sensitizing 
and developing of the plates, etc., is exactly the same as with 
direct negatives. 

(c.) Stripping Negatives. 

There are various directions for making stripping negatives. 

An india-rubber solution, consisting of equal parts of benzole and 
chloroform, in which an equal part by weight of india-rubber is dis¬ 
solved, is used as a substratum. When the solution has become 
quite clear, the unrevprsed and unvarnished negative is coated with 

it. When the film is dry, a coating of raw collodion, to which some 
drops of castor oil have been added, is given. When this film is 
quite dry, it is cut through near the edges with a sharp knife, and 
the glass plate and film placed in a dish filled with water, when 
the negative film will loosen from the glass and after some time 
will swim in the water. In this operation the use of force must 
be avoided. The film is lifted from the water by placing a card 


46 


PHOTO-LITHOGRAPHY. 


underneath it, carefully dried with fibre paper, then laid flat and 
pressed somewhat between tissue paper. The negative prepared 
in this way has many disadvantages. First of all, the film is easily 
injured, and, therefore, the edges should be bound with strips of 
paper in order to protect it from tearing; further, the film is 
easily folded and does not remain accurately of the same size, 
which makes it useless for certain purposes. Moreover, this 
process is somewhat costly. It is now almost entirely replaced by 
a process in which a gelatine substratum is used. 

This process is as follows:—The unvarnished negative is 
accurately levelled with a level and coated 2 mm. thick with a 
solution of— 

White gelatine... ... ... 20 parts by weight. 

Distilled water ... ... 500 „ „ 

Glycerine (chemically pure)... 25 ,, „ 

Glacial acetic acid ... ... 10 „ „ 

Alcohol 36 ° 0 ... ... ... 50 „ „ 

The above quantity is quite sufficient for at least four negatives 
21 x 26 cm. Many omit the acetic acid, but I have found that 
it is an advantage for the slow drying, the pliability, and the keep¬ 
ing of its size of the negative, to use acetic acid in moderate 
quantities. To a certain degree the addition of glycerine also 
effects this, but not sufficiently enough. Before pouring on the 
gelatine solution, the plate must be absolutely dry. Any air bells 
formed whilst coating must be pushed to the edge of the plate 
with a piece of card. The plate must be dried spontaneously in 
a room as airy and as free from dust as possible. In order to pro¬ 
tect the film from dust particles, it is advisable to give it a paper 
cap or cardboard cover, which allows the access of air, ancT 
obviously it ought not to touch the film. 

When the gelatine film has become thoroughly hard, it should 
be coated with negative varnish, and, after again drying, should 
be cut round the edges with a sharp knife right through to the 
glass and stripped from the plate. 

If the glass was well-cleaned and prepared, as has been 
previously described on page 41, any gelatine film thus prepared 
will well and safely strip without a substratum. 

With dirty or old plates, a substratum of a 1-2 °/ solution of 
india-rubber should be used. 

After stripping, the gelatine films are best kept between filter- 
papers and under glass plates. 


THE GELATINE. 


47 


CHAPTER III. 

PHOTO-LITHOGRAPHY BY THE TRANSFER OF A GREASY PRINT ON TO 
STONE OR ZINC. 

1. The Home Preparation of Bichromated Gelatine Papers. 

Photo-lithographic or gelatine papers are articles of commerce 
and entirely fulfil their purpose, and must before use be sensitized 
in a bichromate bath. In establishments where much photo-litho¬ 
graphic paper is not used, it is better to obtain it commercially from 
some reliable firm and not to make it oneself, as this is somewhat 
troublesome, and requires special appliances, some practice and 
experience, and with small consumption does not pay. 

For those who are interested in the preparation of chromated 
gelatine paper I will now give the method, and I would remark that 
this paper possesses all the necessary qualities for this process. 

A sheet of well-sized paper is soaked in a bath of cold water, or 
evenly damped with a clean pad, till it has become slimy. The 
water is allowed to drain off, and then the sheet of paper placed on 
a plate of glass which has been accurately levelled, and which 
rests on a levelling stand with screws, so that it can be easily 
levelled. By placing over it a sheet of blotting paper and squeegee¬ 
ing with an india-rubber or flannel squeegee the air bells between 
the paper and glass are removed and any excess of water pressed 
out. Then the edges of the sheet are bent up to about the depth of 
2 cm., and wood or iron rods laid outside, and a warm 1: 30 gelatine 
solution poured on to it. A sheet 70 by 70 cm. will require 
305 g., that is 7'5 g. of gelatine and 297‘5 g. of water. The 
gelatine will set in a few minutes, when the sheet is removed from 
the glass and laid on a rack in a place free from dust to com¬ 
pletely dry, and should remain from a day and a half to two days. 
Such gelatinized sheets can be kept in stock, and will keep fit for 
use in a cool, dry place for from six to eight months. For this 
purpose only good pure rag paper should be used, as the ordinary 
cheap papers contaip many additions which render them unsuit¬ 
able for this work. 

(a.) The Gelatine. 

The gelatine must possess certain qualities, of which the prin¬ 
cipal are as follows. Before all things it must be pure and free 
from grease, or else small round pits form on the surface, which 
give rise to troubles in developing and printing, and only produce 


48 


PHOTO-LITHOGRAPH Y. 


defective transfers. A large proportion of carbonic acid will pro* 
duce the same faults, which may, however, be remedied by a small 
addition of ammonia shortly before use. 

Gelatine is very hygroscopic, and therefore attracts moisture 
from the room where it is kept and dissolves completely in warm 
water. Even in very great dilution, e.g., 1 :100, it sets again to a 
jelly in the cold, but loses the setting power after being repeatedly 
warmed, or if the temperature was raised considerably higher than 
was necessary to melt it. Damp gelatine decomposes in the air 
very soon; the decomposition, however, can be delayed with 
salicylic and carbolic acids and glycerine. Greasy gelatine can be 
improved by the addition of 5 per cent, of alcohol. Too soft 
gelatine can be hardened with chrome alum, and one part of 
chrome alum may be used to 200 parts of gelatine, and by this 
addition the melting point is raised about 7°C. Too hard gelatine 
giyes rise to the formation of bubbles. If the gelatine solution is 
slightly acid it is not a disadvantage. 

The gelatine used in our establishment is of French make, and 
is known as “ transparent white gelatine,” and is also very suitable 
for collotype. I mention this because the gelatine frequently gives 
rise to failure. For practical work, then, it is advisable to stick 
to one make when it has been proved to be absolutely satisfactory. 

To those who would study more closely this very important 
material for photo-lithography and collotype, I would strongly re¬ 
commend the brochure “ Ueber die Reactionen der Chromsauren 
und der Chromate auf Gelatine, Gummi, Zucker und audere Sub- 
stanzeu organischen Ursprunges in ihrer Beziehung zur Chromat- 
photographie,” by Professor Eder, in which the most exhaustive 
information on the application of these two materials so important 
in photography, gelatine and the chromate salts, is given in a 
concise, popular, and easily understood form. 

(b.) The Chromate Salts. 

The sensitiveness to light of the different chromium compounds 
forms at present the foundation of several photographic and photo¬ 
mechanical processes. 

According to Dr. Eder, Vauquelin discovered in the year 1798 
chromium and chromic acid, and made at the same time the obser¬ 
vation that chromic acid formed with silver a carmine red salt, 
which became purple-red by the action of light. In the year 
.1832 the philosopher Dr. Gustav Suckow, in his work, “ Die 
■chemischen Wirkungen des Lichtes,” stated that the chromate 
salts were also sensitive to light in the absence of silver if an 
organic substance was added, as in the light lower (green) oxida¬ 
tion products were formed. In 1839 Ponton added to Vauquelin’s 
andSuckow’s discoveries, and discovered the photographic applica¬ 
tion of chromate of silver, the light-sensitiveness of potassium bi¬ 
chromate on paper. The chromates are per se stable in light; in the 


SENSITIZING. 


49 


presence of organic substances, however, such as gelatine, albumen, 
gum, etc., a quick reduction of the same takes place in light. Talbot 
finally found that a mixture of gelatine and a chromate became 
brown in light, and lostat the same time its solubility in warm water 
and its power of swelling up in cold water. According to the same 
authority simple potassium chromate is from 20 to 25 times less 
sensitive to light than potassium bichromate, and the simple 
ammonium chromate shows the same sensitiveness to light as 
ammonium bichromate. For photo-lithography the latter salt, 
potassium bichromate, is very important, and it has the chemical 
formula of K 2 Cr 2 0 7 . 

(c.) The Gelatinizing. 

The gelatinizing of the paper and the preparation of the gelatine 
solution is effected as follows :— 

The gelatine, accurately weighed out, is placed in small pieces in 
the proper quantity of water, either in a large measure or some 
other vessel, and placed in a water bath and immediately heated. 
It is advisable to place the vessel containing the gelatine into the 
water bath before the latter is heated, so that both may heat 
together and fracture of the glass be thus avoided When the 
gelatine is completely dissolved the warm solution is filtered 
through a linen filter, and so that it may not be cooled the vessel 
into which the gelatine solution is filtered is also placed in the 
water bath. 

Whilst still warm and liquid the gelatine is poured on to the 
previously prepared paper, and any bubbles of air brought to the 
edge of the sheet with a strip of stiff paper or a feather. 

It should be especially noted the gelatine solution should be 
used up as quickly as possible or else it will deteriorate. Gelatine 
which remains for a long time in a state of solution becomes soft 
and fluid, and if the chromate bath is not well cooled a partial or 
complete dissolving of the same takes place in sensitizing or later 
in washing and developing. 

(d.) Sensitizing. 

The first thing to be treated of is the preparation of the bichro¬ 
mate bath. The necessary quantity of the bichromate of potash 
is rubbed up as fine as possible in a porcelain mortar with a little 
water; it should then be transferred to a larger flask and tho 
necessary quantity of water added. When all the bichromate ,ti 
dissolved the solution should be filtered, and so much ammonia 
added as will convert the orange yellow colour into a straw yellow. 
This bath can be kept, in a dark cool room, fit for use for a long 
time. The proportions for the solution are — 

Potassium bichromate ... ... ... I part 

Water ... ... ••• ••• ••• 15 parts 

£ 


oO 


i rtOTCV'THTHOGRAPll f. 


Hriri as much ammonia as will make it straw coloured. The bath 
is neutralized with ammonia or a soda or potassium salt, because 
solutions the bichromate salts have the property of dissolving 
gelatine even in the cold. 

The day before being used the sheet of gelatinized paper is 
placed in this bichromate bath, which should be as cold as 
possible ; in summer it should be cooled with ice. It should be 
completely immersed in this bath, so that the solution covers every 
part of the sheet to the depth of 1-2 cm., and should be left in it 
about three minutes; care must be taken that no air bells form on 
the gelatine. If this should happen they should be removed with 
a soft brush, which ought not to be used for any other purpose. 
On the places not covered by the bichromate solution, which has 
been kept off by the air bells, the paper would not be sensitive to 

,i s ht - 

For ordinary printing the paper may be dried in the air by 
placing it on a board, or better on a rack ; for better class work, 
and actually for all work, it is better to squeegee the paper 
as soon as it is removed from the bichromate bath on a sheet of 
plate glass which has been well cleaned and polished with talc, 
the excess of solution or any air bubbles being removed by 
squeegeeing thoroughly under blotting-paper. IVlany operators 
siigbtly grease the glass plate. I have found that this is not 
necessary if a sufficiently cold sensitizing bath is used, the plate 
glass thoroughly cleaned and well rubbed with talc, and it is dried 
in an airy room. It is advisable to see that there is always venti¬ 
lation in the drying room, and the more this is done the better the 
paper will behave in the subsequent operations. 

To completely dry, the paper requires when drying by itself — 
from three to four hours ; from ten to twelve hours when squeegeed 
to glass. The best way is to sensitize the paper in the afternoon 
cr the evening, so that it may be used the next day in the morn¬ 
ing. The paper when sensitized will, when properly kept in a 
dark cool room, be in a fit state to use for several days. By 
squeegeeing on to the plate glass the paper takes a very high 
glossy surface, and thus in printing comes into intimate close 
contact with the negative. In exposing, therefore, every fine line 
appears with greater precision than on paper which has become 
wrinkled and uneven, and which has not been previously glazed. 

It should also be mentioned that this gloss is frequently obtained 
by burnishing the sensitized paper when dry. 

(e.) The Printing. 

A.fter the paper has been sensitized and well dried it is printed. 

The negative is first laid in the printing frame film side up. 
Then the paper is laid with the sensitive yellow side on the nega¬ 
tive, ana the frame closed. Before it is placed in the light, caro 


THE INKING UP AND DEVELOPING. 


51 


should be taken to see that the paper lies closely everywhere on 
the negative, otherwise it will in parts be indistinct, and the prist 
be useless. For estimating the correct exposure a photometer 
should be used, and I take as an example Vogel’s Fig. 6. 



Fig. 6. 


When beautiful clear negatives are used they should be printed 
to 14 to 16 degrees Vogel. Obviously no strict instructions can bo 
given for every case, and it will be dependent on the quality of the 
negative and the object. 

If the negative has to be covered, or any other dodge used, the 
time of exposure must of course be arranged accordingly. As a 
general guide it may be stated that the details of the picture 
should appear brown and distinct from the ground when the print 
has been correctly exposed. This examination of the picture must 
be done in a dark room, and only one side of the printing frame 
should be opened, so that the print does not shift. If it is over¬ 
printed, the picture develops badly, the lines become broader, the 
details disappear in the deep shadows, and the ink adheres to the 
unexposed parts. If, on the contrary, it is under-printed, the ink 
does not adhere well to the exposed places, and washes off in 
developing from the fine parts. Practice, as with all manipulations, 
is necessary, and therefore one must not be disheartened by the first 
failure. 


(f.) The Inking Up and Developing. 

As soon as one is satisfied that the exposure is sufficient, the 
print should be taken from the frame in the dark room. The 
next process is inking up and developing. This is effected in 
various ways; the ink is either spread on the dry print with a 
velvet roller or a thin developing ink is used with a brush, or the 
bichromate is first washed out and then the ink spread on. I 
prefer to ink up the print with a velvet roller, on which is the 
developing ink, before washing. By this method I obtain between 
ink and gelatine the soluble chromium film. The print develops 
then very quickly and well. For this purpose it is laid on a glass 
plate, a litho stone or any other flat surface, a small quantity of 
good litho transfer ink is distributed on an inking stone with an 
>rdinary litho roller, and the velvet roller charged with the ink 












52 


PHOTO-LITHOGRAPHY. 


from the sto&o by rolling it several times over the stone. The 
print is now rolled up with the velvet roller till it appears of a 
general grey tone ; the details of the picture, however, are still 
visible through the ink. With this first inking up, too little 
rather than too much ink should be used. When the inking up 
is finished, the print should be laid in cold water, care being 
taken that no air bells form on the surface, and it is also advis¬ 
able to frequently turn the paper over once or twice in the water. 
After ten or fifteen minutes a change will be seen on the print, 
the exposed parts will be somewhat more depressed than the un- 
exposed, which will have swollen to some extent in the water. 
The print is now taken out of the water and spread out exposed 
side up on a sheet of glass, very carefully avoiding folds, and 
dried with blotting paper, and the water which is on the back of 
the print is removed by strong pressure on the print from the 
front. 

The print whilst still damp is again for a second time rolled 
up with the velvet roller, by which means the details of the 
drawing again take the ink. From the unexposed parts the ink 
now goes on to the roller, in exactly the same way as in cleaning 
the litho stone, and they appear covered now with a very faint 
tone. If the first rolling up was done with too much ink, it will 
be accompanied by two disadvantages. Firstly, that too much 
ink will adhere to the details of the drawing, and there will be 
the danger that in transferring the same will appear thick, and 
secondly the tint will not be so well removed from the unprinted 
parts, which will produce a difficult development. It is therefore 
advantageous only to give in the second inking the printed parts 
the quantity of ink requisite for transfer. 

After being inked up a second time the print is again placed 
for a short time in the water, then taken out, spread out on the 
sheet of glass, and now completely developed with a pad or a 
tuft of cotton wool. This is effected by going over all the print 
with light pressure and not too quickly with a circular move¬ 
ment, till the drawing appears quite clear and clean on a white 
ground. In this operation it is advisable to use as much water 
as possible, in order to remove all the bichromate from the print, 
which might be troublesome in the subsequent operations. The 
washing should not therefore be stopped till the unexposed parts 
have lost all yellow tinge and appear nearly white. If the 
bichromate remains in the unexposed parts, the process continues 
during the drying of the print; these places then become hardened, 
and are frequently the cause of an unsatisfactory transfer. One 
of the chief requisites is, however , that too much ink should not he used 
in inking up. The developed drawing should not appear deep black , 
hut grey , yet covered in all places. The developing ink contains so 
large" a quantity of grease that the least quantity is sufficient to 
form the combination previously described on the stone. 


husnik’s photo-lithographic paper. 


The developed print is freed from all adhering water by pres¬ 
sure with half-damp blotting-paper, and then fastened on to a 
board with drawing pins to completely dry. 

The room where the development is carried on should be well 
ventilated, and not be heated too much, as the latter makes the 
work more difficult. The drying ought not to be forced and 
should be allowed to take place spontaneously at the ordinary 
temperature of the room. 

For transfer to zinc and for sending photo-lithographic prints 
it is advisable to bathe them in a 10 per cent, solution of alum for 
about five minutes, so that the gelatine film is hardened. When 
the prints are to be used or to be transferred to stone immediately 
this treatment may be omitted without harm. 

2. Various other Photo-lithographic Papers. 

The paper described above is a pure gelatine paper, and 
although this has proved in practice to be satisfactory for all 
work that may arise, still I will describe some other papers, 
which have been also used in practice with good results, and for 
those who do not care to prepare their own paper they have the 
advantage that they may be obtained commercially. 

Albumen was used first instead of gelatine and rendered sen¬ 
sitive by the addition of a chromium salt. This paper had the dis¬ 
advantage that it could not be kept, and only sufficient paper and 
albumen solution for one day’s work could be prepared. A much 
greater disadvantage, however, was that in developing, the 
albumen film was rubbed off with the pad, and the paper was 
more or less rubbed up. A tint was produced through this 
which transferred to the stone, and thus gave rise to considerable 
troublesome and tedious retouching. This is not the case, however, 
with the gelatine coating, which is comparatively more resistant. 

(a.) Husnik’s Photo-lithographic Paper. 

Prof. Husnik has combined these two procesess for the produc¬ 
tion of his papers, as he gives a coating of albumen to a paper 
coated with gelatine, which should be rendered sensitive with 
ammonium bichromate. By this means is, on the one hand, the 
rubbing up of the paper prevented and damage to the image not 
easily possible; on the other hand, the development takes place 
very quickly, as the albumen film dissolves and can be easily 
removed with the greasy ink. Husnik specially contends that 
with the use of these papers he obtains extraordinarily sharp 
images without any tint. The sheets thus prepared will only keep, 
however, one or two days, and this inconvenient operation has to 
be repeated every time before using the paper. This applies also 
to the albumen solution, so Husnik has come to the conclusion that 
it is better and more practical to use plain gelatine paper; but 


^4 


PHOTO-LITHOGRAPHY. 


tvhen trouble, time, and cost are not of such great consideration, 
then it is better to use the paper with the compound coating, as it 
enables less experienced operators to produce good work. 

The paper more recently produced by Husnik is a pure gelatine 
paper, which is rendered sensitive to light in — 

Ammonium bichromate ... ... 1 part 

Water ... ... ... ... ... 15 parts 

Alcohol (ordinary) ... ... ... 4 „ 

4s much ammonia is added to the bichromate solution as will con- 
rert the reddish colour into yellow, and the bath smells of 
ammonia. The bathing of the paper must be done as quickly as 
possible, and the sheet should only be drawn through the solution. 
The exposure for this paper is from one to three minutes in the 
sun, or from ten. to thirty minutes in diffused light. 

The inking up of the print should be done with a greasy transfer 
ink, to which one-sixth part of wax has been added, and the whole 
dissolved in turpentine to the consistence of oil. The print is 
inked up with this thin ink, and then gone over with a pad of 
cotton wool till it has taken an even gray tint. 

When the turpentine has evaporated the print is laid in cold 
water, and, after about ten minutes, developed with a soft thick 
pad with a continuous circular movement and quite light pressure. 
After development all adhering water is removed from the print 
with damp blotting-paper, and the transfer can be effected after 
from fifteen to twenty minutes. 

Husnik, however, did not rest, and soon prepared a still bettor 
paper, which is known at the present time commercially as 
“ Husnik’s Autotypic Paper.” He produces this paper in large- 
quantities, the coating of the gelatine being effected by machines, 
which certainly tends to ensure equality. 

Husnik found that by the use of less concentrated bichromate 
baths the fine lines were stronger-after printing than from the 
nature of the negative they should be. From one and the same 
negative there was obtained by the use of a bichromate bath of 
1: 100 a relief five times as broad as when a bath of 1 :15 was used 
to sensitize the paper. This he ascribes to the colour of the 
gelatine being less, so that more rays of light penetrated to the 
surface of the paper, from which it would be again reflected, and 
every point or line again reproduced, w r hich must obviously lead to 
an increase of the size of the same; on the other hand, with 
strongly chromated paper, the rays of light would not only be 
absorbed by the intense yellow colour of the chromium salt, but 
still more by the brown tone formed immediately after printing, 
which makes a reflection impossible. With autotype negatives 
this is specially striking, as with weakly-chromated paper black 
shadows without details occur, because here the quantity of light 
is distributed by reflection over the fine points, and they will 


PHOTO-LITHOGRAPHIC PAPER BY ADALBERT FRANZ. 


55 


therefore become thicker. When using strongly-chromated papers 
the details in the shadows appear open, clear, and sharp. 

The concentration of the bichromate bath cannot be increased at 
will, because other disadvantages are produced, especially such a 
firm adherence of the greasy ink to the print that it transfers 
badly and a part of it always remains behind. The bichromate 
salt, when as strong as 1:18, dissolves the gelatine at ordinary 
temperatures, and the baths, neutralized with ammonia, have the 
disadvantage that the greasy ink adheres too little to the print 
and will be rubbed away in developing the drawing. In order to 
entirely obviate the reflection of the rays of light Husnik uses an 
addition to the gelatine besides a 1 : 22 acid bichromate bath, which 
produces a pure yellow tone in sensitizing the papers, is insoluble, 
and completely penetrates the film of gelatine, so that a reflection 
of the chemically active rays is entirely avoided. 

This paper, which is also darker coloured, does not allow the 
light rays to pass through, and is specially suitable for the transfer 
of autotypes to stone or zinc. 

For sensitising this paper bichromate of potassium, sodium, or 
ammonium is used, but the sodium salt has acted the best. 

In winter a 1 to 20 bath is best; in summer, 1 : 22 or 1 : 24. The 
treatment of the paper, as well as of the print, is exactly the same, 
as with other transfer papers. The bath will keep for fourteen 
days. Caustic ammonia ought not to be used. 

(b.) Photo-lithographic Paper by Adalbert Franz. 

A photo-lithographic paper, ‘with which I have obtained very 
good results on stone as well as on zinc, with all kinds of drawings 
is sold.by A. Franz. 

This is also a pure gelatine paper. But Franz adds to the gela¬ 
tine solution manganese sulphate (this must not be confounded witt 
manganese borate, siccative powder, which makes the transfer ink 
dry so quickly that a transfer to the stone or zinc is impossible). 

Through the researches of MM. Lumiere the manganese salts 
have gained considerably in importance, and they have been intro¬ 
duced into photo-mechanical processes. When an addition of 
about 10% of manganese sulphate is made to the acid bichromate 
baths for sensitizing photo-lithographic papers, the printed places 
assume a very much darker colour, which is an advantage in 
judging the print, in developing the finest lines, and points are 
retained much more easily than on paper sensitized with the 
addition of ammonia. 

This paper possesses the advantage, which is also more impor¬ 
tant, that the—especially in summer—unpleasant ammonia bath 
need not be used. The paper is sensitized in a solution of— 
Potassium bichromate ... ... 40-50 g. 

Manganese sulphate ... ... ... 5 „ 

Water... ... ... ••• ... 1 litre 


56 


PHOTO-LITHOGRAPHY. 


Ammonium bichromate ought not to be used. The bath would 
then become cloudy immediately, and both bath and paper made 
useless. 

When sensitized the paper can be kept from eight to ten days 
without losing its good qualities. 

With this a transfer ink is supplied in tubes, which must b& 
mixed with an equal volume of turpentine and benzine, so that 
it becomes quite fluid. The print, when it is taken from the frame, 
is fastened on a board with drawing pins, and with a fine camel’s 
hair brush coated with this fluid ink as evenly as possible, and just 
so much that a light grey tone is formed on the print. This paper 
must not be inked up with a roller. As soon as the turpentine 
and benzine have evaporated the print is laid in cold water, and 
after about ten minutes developed with a clean tuft of cotton wool. 
The print does not show a strong relief; the development takes 
place quickly and regularly. The ink, in spite of its being so thin, 
is very greasy, so that only a very light skin is necessary for the 
subsequent transfer. The tint produced bj a negative slightlytoo 
thin cannot be easily removed. 

The other operations are the same as for the other photo-litho- 
jraphic papers. 

Franz’s photo-lithographic paper is characterized, as already 
mentioned, by giving extraordinarily sharp clean tranfers, which, 
indeed, may be due to the use of the very thin liquid greasy ink. It 
is, therefore, especially to be commended for very fine work. 

(c.) Albert’s Photo-lithographic Paper. 

August Albert’s is also a very good photo-lithographic paper._ 
It can be obtained commercially in two qualities, viz., “ Photo-litho-"* 
graphic paper” and “Autotypic high glaze paper.” This has 
been tested in the K.K. Lehr-und Yersuchsanstalt fiir Photo¬ 
graphic und Reproductionsverfahren in Vienna, and has received 
a certificate of excellence. The high glaze paper has a prepared 
film of several coatings; the developed prints when dry keep the 
high glaze. 

The sensitizing bath consists of— 

Water ... ... ... 16 parts by weight 

Potassium bichromate ... 1 part „ 

Alcohol (ordinary) ... 4 parts „ 

and to this so much ammonia is added as will convert the reddish 
colour into a light yellow; a small excess of ammonia does no 
harm. The bichromate bath should not have a lower temperature 
than + 15° R, or else the solution cannot penetrate the film 
sufficiently, which results in a defective development. The dura¬ 
tion of sensitizing is from four to eight minutes, till the paper is 
quite soft and damped through. It is preferable to sensitize too* 
long rather than too short. 


TREATMENT OF THE PRINT AND THE PLATE. 


57 


The paper should be squeegeed on to plate-glass, as already 
described, and allowed to dry spontaneously. The paper when 
stripped from the plate-glass shows a beautiful high glaze, and ea:, 
be kept fit for use for twenty-four hours. When the paper is oldei 
it can still be used, but the development is more difficult, and it h 
better to avoid this for fine drawings or autotypes. 

Albert does not recommend a photometer to be used when 
printing this paper, but by examination of the print to judge 
when this is correct. The image should have a brown tone, and 
be easily distinguished by the eye from the ground. Over-print¬ 
ing is disadvantageous, as the lines and points become broader, the 
prints develop badly, the tint adheres firmly to the ground, and 
the details in the deepest shadows are lost. 

The inking and developing can be done by any of the known 
processes which is thought desirable. The chief thing is that too 
much ink must not be used in the first inking up; any intensifica' 
tion required may be effected with a second coating. This is, 
especially for fine drawings and autotypes, very important, whilst 
for coarser work also once inking is sufficient. The prints are then 
placed in cold water, and after sufficient washing should be 
developed with a soft pad or pad of wool, with which any tint can 
be very easily removed from any parts which should remain white. 

3 The Photo-lithographic Transfer. 

(a) Treatment of the Photo-lithographic Print and the Plate. 

The transfer from the bichromated gelatine paper requires 
generally, as regards treatment and choice of the material, greater 
care on the part of the printer than an ordinary transfer, and this 
increases in transferring fine drawings or autotypes on to stone. 

In the first place the good quality of the stone should be looked 
to. For ordinary or coarsely drawn subjects this is of less impor¬ 
tance, but for fine drawings and autotypes it is of the highest 
importance. Further, accuracy and cleanliness are all important, 
without which successful work is impossible. On the other hand, 
a transfer can hardly fail if it be accurately and correctly per¬ 
formed. 

When the print comes from the developing bath, and has been 
well washed so that every trace of bichromate is removed, it should 
be freed from excess of water between blotting-paper. It should 
then be dried in a^ not too warm place free from dust till the 
gelatine has completely set and feels absolutely dry. The relief 
will have now again disappeared, and the black and white places 
lie in the same plane. It is best dried by pinning it to a board 
with drawing pins, and then set up in a dry place. 

In the meanwhile the transfer stone should be prepared, which 
must be absolutely faultless. Just before the transfer it should 
be dry polished with pumice stone, and then well dusted with a 


58 


PHOTO-LITH OG K A PH Y. 


cloth. The slightest grain will give a spot in a fine tone. 
Obviously the stone must be well ground so that neither any 
spots nor lines of an earlier transfer can appear. With an open 
drawing this can be corrected, but not with an autotype ; in such 
a case the shortest way is to make a new print and a new transfer. 

The print is first wiped over on the back with a damp cloth, and 
then laid on damp blotting-paper. After about five minutes the 
print is treated a second time with a damp cloth, and then laid 
between damp blotting-paper. It is not advisable to lay the print 
between ordinary damp blotting-paper, as the gelatine becomes 
somewhat sticky, and would attract particles from the rough 
paper. 

The degree of dampness which is necessary for transfer may be 
judged in that the print must feel soft, but the gelatine film ought 
not to be very sticky. Any further preparation of the print before 
transferring to the stone is not necessary. The print is laid on the 
stone, over it a dry sheet, and then the cover, and then drawn 
through the first time with light pressure. 

In order to prove whether the transfer has taken well a corner 
may be lifted up. All the ink which was on the print must be 
transferred to the stone, and then the transfer has been completed 
in the correct way. The print is now pulled off the stone and the 
transfer made ready, like any other. 

With this method of treatment the print will strip easily, which 
is not the case if it was not well dried after the developing bath; 
a much sharper and cleaner transfer will also ensue. If the print 
was too damp a fuzzy, broken-down transfer will be obtained, 
because the gelatine, which has become too soft, will be broken 
down. 

I will also mention that it is not advisable to treat fine drawings 
or autotypes with the rubbing-up pad. It is better to go over the 
transfer with the roller, and the tones are kept cleaner. The stone 
is then gummed, placed on one side, and allowed to stand some 
hours before being etched. 

For transferring to zinc plates which are to be etched or to be 
printed from, the bichromated gelatine print should be bathed in a 
ten per cent, solution of alum, allowed to dry, and then, as 
previously described, damped, and then transferred under the 
same conditions as to stone. 

It only remains to mention that the stone or zinc plate should 
not be too cold. 

(b.) Failures tn the Photo-lithographic Transfers. 

The failures or faults which are met with in photo-lithographic 
transfer may be caused by various things. 

The squashing dovrn rarely happens with photo-litho transfer, 
because a good photo-lithographic paper will bear a considerable 


FAILURES IN THE TRANSFERS. 


59 


amount of dampness. When, however, it occurs it may be assumed 
that either too strong pressure or insufficient care in the setting of 
the stone is the cause. Much more frequently it happens that 
some parts of the print do not transfer at all, or only in a defective 
manner. The chief reason of this is that the print was insufficiently 
damped. This frequently happens if ordinary or gravure prints 
are to be transferred with photo-lithographic prints. If the printer 
encloses the impression on the ordinary transfer paper and the 
photo-lithographic together in the same damp sheet, and if he 
estimates the degree of dampness from the gravure print, the 
photo-litho paper will be insufficiently damped and a good transfer 
will not be obtained from the latter. If, however, he waits till the 
photo-litho paper is damp enough, the other impressions will be too 
damp and will squash out in transfer. For such work the print 
on ordinary transfer paper and the photo-lithographic print should 
be kept separate, so that the different dampness requisite for each 
can be regulated. 

Another case which frequently happens is that the print is 
contaminated with particles of dust or other foreign substances. 
These may be flying about in the air or be on the stone, the roller, 
or the damping paper. Through this many transfers of fine 
drawings are rendered useless. Perfect cleanliness of the utensils 
and the use of the correct ones, combined with a drying-room for 
the print absolutely free from dust, are absolutely essential for 
faultless work. 

The composition of the ink, especially if it was too hard, may 
give rise to bad transfers. 

Photo-lithographic papers, which are prepared with very hard 
gelatine, must be laid before transferring in lukewarm water. By 
this means the hard gelatine becomes rather sticky, and the greasy 
ink transfers much better. Even those points which in developing 
have taken up little ink, and appear grey, transfer completely to 
the stone and adhere firmly. 


60 


PHOTO-LITHOGRAPHY. 


CHAPTER IV. 

PHOTO-LITHOGRAPHY BY DIRECT PRINTING ON TO STONE OR ZINC. 

The processes of photo-lithography previously described are based 
upon the printing on to bichromated gelatine or albumen paper 
development with a greasy ink and subsequent transference of 
the greasy print to plate or stone. A process may also be used in 
which the stone or plate is printed on direct. There are in this 
various methods, of which the principal are printing on to light- 
sensitive asphalt, or an organic substance, gelatine or albumen, in 
combination with a bichromate salt. The reason is the high 
sensitiveness, which is possible, of the substances used. 

1. THE ASPHALT PROCESS. 

(a.) The Light-Sensitive Asphalt. 

Light-sensitive, or so-called Syrian, asphalt, which is prepared 
for photo-lithographic and photo-zincographic purposes, can be 
obtained from various firms who deal in photographic goods, and 
one has only to dissolve the same according to the prescribed 
directions. This kind of asphalt is, however, not very sensitive, 
and in use must be printed for some considerable time. If, there¬ 
fore, an asphalt of greater sensitiveness is desired it is not suffi¬ 
cient to merely dissolve Syrian asphalt, but it must undergo a pre-^. 
liminary preparation. 

Only that part of the asphalt is sensitive or useable for photo¬ 
lithographic work which does not dissolve in ether. The insensi¬ 
tive part must, therefore, be separated out, which is done by 
finely powdering the asphalt, sifting it through a fine sieve, and 
then treating it with ether. All that is soluble in ether goes into 
solution ; the marc which is not soluble in ether is then dissolved 
in benzole and used as wanted. 

( a .) Hosnik’s Process. 

Professor Husnik has improved this process in so far that he 
does not dissolve the asphalt powder in ether, as, according to his 
view, a complete solution of all the insensitive portion is not 
attained by this process, but he dissolves coarse asphalt pow'der 
completely in rectified spirit of turpentine to the consistence of a 
moderately-thick syrupy mass, until no hard particles or a residue 
are contained in the solution. To this viscous asphalt solution a 
plentiful quantity of ether is added gradually, and with constant 
stirring, and a big flask should be used for this purpose. After a 
sufficient quantity of ether has been added a pitch-like deposit 


valenta’s process. 


61 


separates out at the bottom. In order to test whether there is 
still any light-sensitive asphalt in the supernatant liquor a small 
■quantity is poured into a glass and mixed with ether, when if a 
precipitate ensues more ether must be added to the big flask. 

After standing for about twenty-four hours the ether contains 
all soluble insensitive constituents of the asphalt; the pitch-like 
residue in the flask, after pouring off the solution, is again treated 
with ether, so that all turpentine is extracted and any stray insen¬ 
sitive particles are dissolved. The pitchy residue is now removed 
from the flask and allowed to stand in a porcelain dish in a warm 
place, with frequent stirring, till it is quite freed from ether, and 
has formed a hard, brittle, black shining substance, which can be 
easily broken up into powder with the hand. This product is now 
the light-sensitive asphalt, which is dissolved for use in anhy¬ 
drous benzole. As benzole is only to be obtained anhydrous with 
difficulty, some chloroform is added to the solution in order to 
prevent the running together in drying, whence the film would 
become unequal and patchy. 

The coating of the stone or plate with the asphalt film is very 
simple; it should be placed horizontal, and then whirled rapidly 
on a whirler. 

Printing under a clear negative takes from a quarter to half an 
hour in direct sunlight. 

The picture is developed with turpentine. 

( b .) Valenta’s Process. 

Valenta recommends for photo-lithography asphalt which has 
been sulphurized by the wet process, as it possesses a considerably 
higher light-sensitiveness than that which is not sulphurized.* 

The process is as follows :—100 g. of raw Syrian asphalt are 
boiled in a retort with an equal quantity of raw pseudo-cumene, 
which has the formula C 6 H 3 (CH 3 )3, and a boiling-point of about 
170°C., with 12 g. of flowers of sulphur, which should have been 
previously dissolved in the pseudo-cumene. When after about 
three or four hours’ boiling the evolution of sulphuretted 
hydrogen has ceased, the pseudo-cumene is distilled off and the 
black pitchy residue dissolved in benzole in the proportion of 
4 :100, and used for the preparation of the plate or stone. 

* The sulphurized asphalt prepared in this way is almost insoluble 
in ether, but dissolves fairly readily in benzole, toluene, xylene, 
cumene, and turpentine, and is very sensitive to light. 

With this asphalt good prints are obtained even in bad, 
cloudy weather. For use four parts of the sulphurized asphalt 
are dissolved in 100 parts of benzole, the solution filtered and 
diluted till a thin film on a zinc plate shows a golden yellow colour. 
Exposure of the asphalt solution in an open flask for from half to 
one hour in sunlight is advisable. 

For developing the asphalt image rectified oil of turpentine free 
* Eder’s “ Jahrbuch der Photographie,” 1892, p. 241. 


02 


PHOTO-LITHOGRA PHT. 


from acid is used; the best is French or Austrian. The develop¬ 
ment may he accelerated by adding Hungarian or Russian turpen¬ 
tine, which, however, attack the asphalt image; it can be restrained 
by the addition of ligroin, benzine, or wood oil to the turpentine. 

Zinc plates are best developed in a dish, stones by making a wax 
margin round the drawing. The oil of turpentine is poured on 
and rocked to and fro. Rubbing with a pad of cotton wool, etc., 
should be avoided. After development the plate should be well 
washed under a stream of water, and before gumming, the plates 
should be exposed for some time to light, as this makes the ground 
more resistant to the etching. 


(b.) Coating the Stones. 

The stone or zinc plate is now coated with one of the above- 
described asphalt solutions, or with the following: — 

Asphalt ... ... ... ... 20 g. 


Chloroform 

Benzole 

Oil of Lavender 


300 
100 „ 

20 drops 


The solution must be thin, so that it flows over the stone well 
and does not form unequally-covered patches. 

The subsequent manipulations must be conducted in the dark. 

The stone which is to be used must-be well ground, and polished 
with dry pumice stone, well dusted, and be absolutely flat. It 
ought not to have any depressions, as the negative would not lie 
in contact there. The places would not print sharp, and therefore 
a bad result would be obtained. 

The necessary quantity of the solution is now poured into the 
middle of a well-polished stone, and distributed as evenly as*' 
possible by rocking backwards and forwards. When thoroughly 
distributed the stone should be placed on the whirler and kept for 
some time in motion. The asphalt solution must be as thin as 
possible, so that it appears yellowish-brown and the colour of the 
stone appears through it. If the stone is only covered all over the 
film can be very thin; on the other hand, if it is too thick it will 
not print through, and will develop badly, as too much of the 
asphalt will dissolve. If , zinc plates are used for printing they 
should be prepared as previously described on p. 6. Zinc plates 
for deep etching must be well ground and well polished, and 
ought not to repel water. The zinc plates are coated the same as 
the stone. 


(c.) Printing. 

When the film is absolutely dry, which will be in about fifteen 
minutes, printing may be proceeded with. For this purpose the 
negative is either laid on to the asphalted stone, film side down, 
and pressed down with screw bands, or it is laid, the glass down¬ 
wards, in a specially-constructed and very strongly-built printing 
frame, which is provided with a sheet of plate" glass, and the 



DEVELOPING AND INKING UP. 


63 

asphalted side of the stone laid on this, the printing frame closed, 
and then exposed to light. The exposure continues according to 
the strength of the light and the nature of the negative from 15 
minutes to 1| hours. If the film of asphalt be thin and the 
negative clear it may he printed to 18 or 20 degrees in Vogel’s 
photometer. This kind of printing al ways requires some experience, 
as various factors, such as the thickness of the asphalt film, the 
density of the negative, also the fineness of the drawing, have to 
be taken into account. It will be understood that the asphalt 
film must always be coated as evenly as possible. 

If it is printed too long the stone will not develop at all, or only 
in parts ; if it is printed too little the drawing wholly or partially 
dissolves In both cases an unsatisfactory result will be obtained. 
Negatives very clear in the lines of the drawing, and well covered 
in the ground, are here more essential for success than with the 
chrome gelatine process. 

(d.) Developing and Inking Up. 

When properly printed the frame and the stone should be 
brought into the dark room and development proceeded with. 
For ordinary Syrian asphalt rectified turpentine can be used, and 
one of two methods may be adopted. The stone is laid in a pan as 
straight as possible, and then flowed over with turpentine, which 
should be allowed to remain on it for some time, and then poured 
off into the pan. Fresh turpentine is now applied till the drawing 
appears clear and distinct. The turpentine which is allowed to 
run off can be used for washing purposes. An edging of warm 
gutta-percha may also be made round the drawing, and then 
turpentine poured on to it and the stone rocked up and down till 
the drawing is developed. 

The very sensitive kinds of asphalt of Husnik and Valenta are 
much more readily soluble than the ordinary Syrian asphalt. In 
developing one must go carefully to work, and not allow the 
turpentine to stay on the stone a long time, but to pour it over the 
stone, which should be inclined so that it can run off. This can 
be repeated if required. It can be well and safely developed if 
half and half of turpentine and linseed oil is used, which, how¬ 
ever, has the disadvantage that the stone becomes greasy, but this 
can be taken off by the expert printer. 

After developing the stone should be well washed under a strong 
stream of water, then allowed to dry in the light, as by this the 
asphalt film becomes more capable of standing the etching, 
and then be coated with neutral or very slightly acidulated gum. 
After gumming, the stone is again dried and allowed to stand for 
some hours to rest, after which it can be inked up and etched, and 
finally sharp etched. 

The zinc plate is, after development, also well washed, then 
allowed to dry, treated with thin gum solution, then with an 


64 


PHOTO-LITHOGRAPHY. 


etching solution of tincture of galls or gallic acid and phosphoric 
acid, and inked up. 

Prints on zinc plates for deep etching are gummed after develop¬ 
ing, and if the asphalt film is perfect without rubbing up with a 
pad, which thickens the drawing, etched for some minutes in very 
dilute nitric acid. 

Many lithographers are accustomed, and indeed it is necessary 
with some transfers, to rub the prints up with greasy ink. 
The process is as follows:—Greasy transfer ink is diluted with 
some turpentine, and after the stone has been gummed and allowed 
to dry, then washed, the drawing is wiped over with a soft pad 
with this dilute ink, when the ink adheres to the drawing, 
strengthens it, and if great care is not taken, thickens it also. 
With asphalt prints this is absolutely useless, and for other direct 
prints, as well also as for good chromated gelatine prints, in most 
cases unnecessary. The exposed asphalt combines so intimately 
with the stone that strengthening with a greasy ink is quite un¬ 
necessary, is indeed absolutely purposeless, as the ink can neither 
penetrate the hard asphalt film nor combine with it. The film of 
asphalt alone is so resistant to every etching solution that it is for 
this reason absolutely useless to strengthen it. 


2. OTHER PROCESSES. 


Besides the asphalt other mixtures of other light-sensitive 
substances may be used for direct printing, and these are mostly 
organic substances in combination with a chromium salt, and 
possess also a greater sensitiveness to light than asphalt. 

The solutions which have been specially used in our establish¬ 
ment consist of — 


(A) . Albumen 

Ammonium bichromate 
Distilled water 
Ammonia 

(B) . Chloroform 

Benzine 

Alcohol 

Mastic... 

Aniline red 


I?' 

500 „ 

15-20 drops 
250 g. 

50 „ 

20 „ 

2 „ 

2 ,, 


Solution A is strongly sensitive to light, and is used for coating 
the stone or zinc plate; with solution B the stone is coated before 
developing. The details of the process are as follows :— 

(a.) Coating the Plates. 

After the stone has been carefully polished and well dusted it 
should be first flowed over with distilled water, in order to 
increase the possibility of spreading the sensitive solution. When 
the water has run off, the stone whilst still damp should be flowed 
over with solution A, and care should be taken that the same is 
evenly distributed and that no bubbles form. The stone should be 






FURTHER MANIPULATIONS. 


65 


placed immediately on the whirler and rotated till the solution is 
dry. Obviously a thick film must be avoided, as in such a case 
the print would not adhere to the stone. 

If a zinc plate be used it must be well prepared and be rendered 
free from grease. To prove this the plate is flowed over with 
distilled water, and when this spreads equally all over and is not 
repelled from any part, the solution can be poured on. If, how¬ 
ever, the plate does not willingly take water everywhere, it must 
be again cleaned or polished. The other operations are the same 
as for the stone. 

(b.) The Printing. 

When the film is quite dry, printing may be proceeded with. 
The duration of printing depends obviously also here again on two 
important factors—the quality of the negative and the strength of 
the light. Under a good negative with absolute bare glass in the 
lines of the drawing I print to about 10° Vogel, for example:— 

In direct sunlight (middle of April, 11 a.m.) ... 2 min. 

In the shade „ „ „ 5 „ 

In electric arc light (3000 c.p., at a distance of 

50 cm. = 20 ins. without reflector) ... 25 „ 

The picture is faintly visible. If the negative was too thin, or if 
it be over-printed, the image develops badly or not at all. With 
under-printing the film washes right away. 

Immediately after printing the stone or plate is coated with 
solution B, which is distributed as evenly as possible by rocking 
backwards and forwards. It is not necessary, however, to obtain 
even distribution with a whirler. The whole of the coated surface 
becomes deep violet. 

(c.) The Development. 

When solution B has become completely dry, the stone is placed 
in a suitable vessel with pure water. After about five minutes the 
places not affected by light dissolve if- the stone is rocked, and it 
is only necessary to go over the drawing with a pad of cotton wool 
to clean the same completely. The drawing now appears a deep 
violet on a bright ground. The development is continued without 
rubbing strongly with the pad—which might rub up the drawing 
—till all the details of the drawing appear clear and distinct. 
This especially applies to the details in the deep shadows. 

(d.) Further Manipulations. 

When the stone or plate is correctly developed, which can be 
easily told, it should be well rinsed and again exposed to make 
the film adhere firmly. It should then be gummed and treated 
as previously described in the asphalt process. The “rubbing 
up ” of the stone or plate is not necessary ; it is better to roll up 
the drawing with an ink roller. Zinc plates for deep etching can 
be lightly etched, then dusted with fine asphalt of resin powder, 
heated and then further etched. 

F 


66 


PHOTO-LITHOGRAPHY. 


It. J. Sachers, of Toronto, Canada, published a sensitive solu¬ 
tion which has the following composition:— 

Distilled water ... .. ... 150 


50 

2 

2 

1 


parts 


part 


Fish glue 

Ammonium bichromate 

Ammonia ... ... ... 

Chromic acid 

This solution is brown, not very transparent, w r ith an olive green 
tinge, and must stand and settle at least twelve hours before it 
can be decanted, filtered, and used. The time of exposure is about— 
Direct sunlight ... ... ... 2-5 minutes 

Diffused light ... ... ... 12-15 „ 

Electric, arc light (3000 c.p., 50 cm.) 30 „ 

The image appears a bright brown on the golden yellow ground 
of the plate. The development is effected in an aqueous solution of 
methyl violet, when the image assumes a beautiful blue violet colour. 
The developed image is hardened with alcohol. The results by 
this method are very good, and although this is recommended for 
half-tone etching, it is also suitable for photo-lithography. 

Excellent results also attend the sensitive “ Marine glue solu¬ 
tion,” prepared by A. Hebensperger, of Munich, to which a second 
solution called “ Chlorogutt-losung ” is added. The sensitiveness 
to light is very high, and the treatment about the same as with 
the first described substance. The “marine glue solution” con¬ 
sists of albumen, bichromate of soda and ammonia. The dye 
solution of Victoria blue dissolved in benzine. 

The process published by Waterhouse consists of coating a 
prepared zinc plate with a thin chromated solution, and then 
drying in a few minutes with a gentle heat- 


(A.) Arrowroot 

Potassium bichromate 
Water ... 

(B.) Alum. 

Water ..*. 

For use mix— 

Solution A ... 
Potassium bichromate.. 
Solution B 


' 2 

9 

7ou 

1 

1 


parts 


part 


40 parts 

5 „ 

15 


This is printed under a reversed negative for about six minutes 
in the sun. The plate is then laid for about half an hour in cold 
water in order to remove the chromium salts, and then cleansed 
from all soluble parts with a pad, and after well washing set up to 
dry. It is then inked up with transfer ink, and after about 
fifteen minutes washed with turpentine. This process, as, indeed, 
all direct printing processes, offers many advantages for prepar¬ 
ing colour plates from a coloured object with one negative. The 
register of the separate plates is very exact, which is not always 
the case with a transfer process. In reproducing line drawings 
the unnecessary parts on the stone or plate can be covered. 




BREAKING UP THE HALF-TONE ON THE NEGATIVE. 


67 


CHAPTER V. 

THE HALF-TONE PROCESS FOR PHOTO-LITHOGRAPHY. 

The half-tone process is used in photo-lithography to reproduce 
originals which do not contain distinct lines or points, but closed 
tones, which are executed either in one or several colours With 
this process any coloured picture, oil, water, pastel, indian-ink or 
sepia drawing, as well as any photographs from nature of living, 
moving scenes, or still life objects can be prepared for reproduc¬ 
tion on the printing press. 

I will first describe briefly the theory of the process, and then 
come to the practical part. 

As regards the photographic part and the quality of the nega¬ 
tives, in the present state of this method of reproduction the 
same principles apply as in line reproduction; where they differ I 
will mention the same. 

The duration of printing, the transfer of the image to the stone, 
as well as the other arrangements will be described in the different 
processes. 

We divide this chapter again into two sections: 

1. Methods in which the half-tone is broken up when making 
the negative. 

2. Those methods in which the formation of the grain is effected 
after the negative has been made by some suitable means. 

1. Breaking up the Half-Tone on the Negative (Autotypy). 

Of the various methods by which a breaking-up of the half¬ 
tones can be obtained, tlje so-called “ autotypy ” is the one most 
used practically. With this process the half-tones are broken up 
in the negative. 

As every important technical discovery is formed not at once, 
but must be made by a longer or shorter series of smaller dis¬ 
coveries or improvements in order to attain the hoped-for goal, so 
was it also with autotypy. 

From the work of Paul Pretsch, Mariot, Brown, and Fred. E. 
Ives the present state of the certain and beautifully-working half¬ 
tone process gradually evolved, and the last process, which ought 
to be considered as the immediate predecessor, is far outshone by 
autotypy as now practised. 

Early attempts were made to obtain a printable image on stone 
by breaking up the chromated gelatine film, so that an irregular 
so-called serpentine grain was formed on it, which corresponded 


68 


PHOTO-LITHOGRAPHY. 


fairly well with the theory of lithography, but gave no precise 
lines and no beautiful gradations of stone. If the grain was 
somewhat too coarse the effect of the picture was lost, the tone 
gradations were too far apart, and only light and shadows were 
given; if the grain was too fine the stone was not printable. 

A further experiment was printing a design over the original, 
the strength of which had to be brought in correct proportion to the 
original; the impressing of a design was also tried, and when 
using this method the correct angle of the incident light when 
making the exposure had to be taken into account. 

Further experiments, which were principally carried out by 
Mariot, Cronenberg, and others, were founded principally on the 
basis of breaking up the tones in printing. For this a lineature 
or screen on glass, or a gelatine film, was introduced between the 
negative and the sensitive film. Others, again, coated the blank 
glass plate with a lineature, and prepared the plate afterwards 
with collodion or gelatine emulsion for the exposure. 

It will be thus seen how this method of reproduction developed 
step by step till net-work of silk muslin or woven horsehair, and 
finally grating images, strongly reduced by photography, were 
placed in front of the photographic plate. 

Thus were efforts made to make half-tone pictures suitable for 
printing by litho- or typography, and although the end was very 
nearly attained, yet the crux was not quite solved. These methods 
did not, however, yield the desired result, namely, a beautiful 
sharp clear image. There was still required a considerable im¬ 
provement of the existing methods, and this was made byMeisen- 
bach, of Munich. 

The principle by which Meisenbach prepared his images was 
essentially different from the previously-described results. He 
broke up the half-tones, also by means of a lineature, into a print¬ 
able grain, but the process was essentially different from the pre¬ 
vious methods, in that Meisenbach used a glass plate on which, on 
a black ground, a grating was drawn till the glass was laid bare, 
and in this way prepared a lineature which consisted of clear glass 
transparent lines and absolutely opaque lines. 

He produced, first, an ordinary negative, from this a positive, 
and from this, by the interposition of the lineature, the actual 
half-tone negative for making the printing plate. The lineature 
or screen was in the second exposure interposed before the sensi¬ 
tive plate, and half the time of exposure given; then the screen 
was turned till the line first obtained crossed the second at an 
angle of 90°, and then the exposure was completed. By this 
means an absolutely certain breaking up of the half-tones into 
mathematically exact points was attained, and the most important 
step made in making photography useful for preparing printing 
plates for the two principal methods, typographic and lithographic. 
Meisenbach has called his process “ autotypy.” It was, indeed, 


BREAKING UP THE HALF-TONE ON THE NEGATIVE. 69 

(Somewhat inconvenient, but bad the advantage that on the nega¬ 
tive and also on the positive any retouching that was necessary 
could be done. 

I cannot here enter into the numerous simplifications and im¬ 
provements of Meisenbach’s process which, as well m the photo¬ 
graphic process as also in the preparation of the lineature, were in 
the course of time made partly by him and partly by Carl 
Angerer, Gillot, Bussod and Valadon, Lefmann, and others, since, 
on the one hand, it would carry us too far, and, on the other hand, 
they may be considered as a natural consequence of the discovery. 
I will only mention that it was found after a short time that the 
two exposures and the production of the necessary positive could 
be omitted, and that the lineature could be simply interposed 
before the sensitive plate in the first exposure, by which an im¬ 
portant simplification of the work was attained, and, thanks to the 
continued perfecting of the processes, no detraction of the good 
results was thus produced. 

I do not consider it superfluous to give a short explanation of 
the action of the interposed lineature on the photographic plate 
during exposure. 

If we take, for the sake of simplicity, not a picture, but a scale 
with four or five-tone gradations from light to deep black, the 
light tones will act more or less on the sensitive photographic 
plate according to their degree of brightness, but as the rays of 
light have to pass through the cross-lined screen interposed be¬ 
tween the lens and sensitive plate, and as the rays can only pass 
through the transparent parts and not through the opaque, no 
homogeneous surface is obtained on the negative, but a tone pro¬ 
duced by the cross-lines of the screen. If the tone was very 
bright, the rays reflected with great intensity on the sensitive will 
completely decompose the silver film. Since they are prevented by 
the screen from acting with equal power on all places of the sur¬ 
face, these places will show very plainly on the negative, and the 
result is therefore a darker tone on the same, which is marked 
with bright fine lines, corresponding in thickness to the screen 
plate. 

If the original tone w*as darker so many rays of light will not be 
reflected, and these have thus not the power to impress the screen 
on the sensitive plate in full intensity; the result is therefore on 
the negative a tone which does not contain such strong dark lines 
as the first; the tone appears lighter in the negative, and in the 
print from the same darker than the first. 

In the reproduction of deep black surfaces finally no rays of 
light are reflected, therefore no rays of light can penetrate through 
the screen, and because actually here no chemical change of the 
light sensitive film takes place, we obtain a negative which is 
clear and transparent in these places, that is to say without any 
interruption, which gives in the print a full black tone. 


70 


PHOTO-LITHOGRAPHY. 


In this process there comes, however, to our aid a very important 
physical law, namely, the diffraction of light. A ray of light 
passing through a round hole or a slit and falling on to a black 
surface is represented not the same size as the slit, but more or 
less broadened the more the receiving surface is moved away, and 
in the middle the brightest light will be, and this gradually fpdes 
off into shadow towards the margin. 

If we take now the opposite, and use instead of the hole or slit 
a black surface or a conglomerate of such in the form of points, 
squares, or other geometrical figures, and if these be placed before 
a screen illuminated with a bright light, these figures become 
somewhat smaller with this bright illumination, whilst with a 
weaker illumination they are represented in correct strength. 

Where the light acts in its full intensity, or in excess, in a 
manner of speaking it is diffracted or bent over the figures, and 
proportionately makes them smaller. 

This law does good service in autotypic work. 

As we have seen, the ra^s of light must pass through the screen 
during exposure. This screen consists of equally thick opaque 
black and transparent white lines. Where the light acts with full 
intensity it will be more diffracted over the black lines. It makes 
the lines of the screen broader on the negative, and will, therefore, 
have more covered places, which in the after printing of the prints 
cannot be penetrated by the light, and thus represent the light 
places in the print covered with fine dots. 

. The darker the tone the less the rays of light reflected, and the 
less, therefore, can the light be diffracted. As the tones get darker 
the lines of the screen become of equal value on the negative, till 
finally, when at the opposite end of the screen, they totally 
disappear in the deep blacks. 

A valuable quality of a correctly-prepared autotype is, therefore, 
that the covered lines or the covered grain appear of different 
strengths on the negative. In the high lights they are stronger, in 
the half-tones weaker, till finally in the black parts they have 
totally disappeared. 

A further not less valuable property is that the grain in the 
highest lights is not sharply defined, does not appear as a square 
point, but is rounded by the diffraction of light, which gives a 
softer, more beautiful appearance and plasticity. 

Whilst the light reflected from the brightest parts of the draw¬ 
ing acts with full intensity,. and is diffracted over the figures 
standing in its path and makes the same smaller, and cuts off the 
sharp corners and gives more covered surfaces to the negative, as 
it decreases according to the more or less deep shadows of the 
drawing, and can only act now with less intensity through the 
open places of the screen, the result is that the points become 
larger, till finally in the deepest parts it is quite inactive, and the 
shadows begin to block. The action of the light rays of different 


BREAKING CP THE HALF-TONE ON THE NEGATIVE. 


71 


strengths reflected on to the negative in accordance with the 
brighter and darker tones of the drawing, taking into consideration 
the print, can be graphically represented as a pyramid of which the 
base represents the deepest shadows and the point the high lights. 
If we interpose a cross-lined screen, or more correctly called a 
grain plate, before the'sensitive plate, we obtain, graphically con¬ 
sidered, grain figures, actually of many more very different sizes, 
as shown in Fig. 7, 1-6, in which the smallest points represent 
the high lights of the drawing, and those becoming gradually 
bigger the gradually increasing shadows. 


1 


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2 


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9 9 9 O 9 

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9 9 9 9 9 


9 9 9 9 9 

* 9 9 9 9 

9 9 9 9 0 


3 


9 9 9 9 9 

» 9 9 9 9 4 

9 9 9 9 <9 

9 9 9 9 9 A 

9 9 9 9 9 

*99994 
9 9 0 9 9 

*99994 
9 9 9 9 9 


r ▼ ▼ v ▼ i 

+ *999 

► * ♦ 9 + 4 

+ 999 + 

> ♦ ♦ ❖ ♦ 4 

4 


^ A ▼ A V A V A ▼ A ^ 

+ + + + w 

> + + + + 4 

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.♦T®>TVV 

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5 

rig. 7 . 


vvwv 

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The original grain plate contained, measured diagonally, five 
black points, five white interstices to the millimetre. The figures 
represent enlargements of a negative made with the above-named 
grain plate, and for this the grain plate was one millimetre distant 
from the sensitive plate. 

The accompanying Figure 8, 1-6, represents very much enlarged 
the scheme of grain of an autotype from a perfectly-executed 
wash drawing, with a screen of five opaque and five transparent 
lines to the millimetre, in equal proportions of black and white, at 
a distance of one millimetre from the sensitive plate, with equal 
time of exposure before and after the turning of the screen, and 
obviously with correct exposure for the whole. 

The scheme is only given here in six gradations of tone. As a 
matter of fact, a good autotype has at least from six to eight times 
the number of tones, as with a sharp screen and an original cleanly 






72 


PHOTO-LITHOGRAPHY. 


and sharply drawn in many tones, the light reflects the least: 
alteration of tone in the size of the grain. 


€>•«•••• 

• ••••©• 

• ® 9 9 • • • 

« O 0 • 0 • © 

• • m ® 9 « • 

® • ® O © 9 • 

© © O * • © • 

© ® ® e » • • 

• 9 O © 9 » • 

• o © ® • • • 

© • © ® © ® • 

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I 9 ® © © © 9 • 

• • e © © © • i 

• © • ® © © • • 

• • « © ©_® © 9 


II 


vX"Xv. 




5 

Fig. 8. 


As previously mentioned, the smallest points represent the- 
highest lights of the drawing ; the larger, according to our graphia 
representation, the darker tones, but a correct reproduction of the^ 
grain. 

In a similar way obviously the formation of the lines on the 
negative behave with an interposed but not revolved screen. Here 
also the lines in the high lights of the negative appear more covered 
than in the shadows. 

The proportion of grain can, if the original requires it, be so far 
altered by not giving equal exposures for each position of the 
screen—for instance, in the proportion of two to one or three to 
one. We obtain then on the given scheme less closed tone grada¬ 
tions, 3, 4, and 5, and just before 3, and between and after 5, tone 
gradations, no single black and white points, but more or less jagged 
black or white lines, whilst the open black grain in 1 and 2 becomes 
more an oval instead of the round form in 6, and beyond the round 
openings are drawn out into ovals. 

We have, however, in autotypy still the physical law, which is 
very useful to us, and that is the greater or less distance of the 
point from the light surface. The nearer a point or a figure is 
brought to the wall on which it should throw the shadow, th& 
greater the size of the original, and so much sharper will be the- 
outlines of the shadows. The more the point or the figure is. 





































































BREAKING UP THE HALF-TONE ON THE NEGATIVE. 


73 


removed from the wall the less the shadow will correspond to the 
shape of the original; it will he smaller and less defined. The 
shape will also frequently change, and a square will become a 
round. We have then in the near or distant position of the 
lineature to the sensitive plate, on which it throws its shadow, an 
important assistance to act on the general tone gradations of the 
image. Let us remember that in focussing the shadow-forming 
object on to the surface on which the light falls, we obtain the 
same formed in all its actuality on the receiving surface ; therefore, 
when this refers to a lineature with equal proportions of black and 
white, we obtain these in equal ratio. When, however, we remove 
the lineature from the light-receiving surface, the shadows which 
it throws contract, the lights predominate, we obtain no longer the 
ratio of 1 : 1 between light and shadow, but about 1*5 : 1 and 
so on. 

By placing the lineature close to the sensitive plate, we obtain 
more closed tones, and as this gradation of tone is carried 
naturally throughout the whole of the image, also less high 
lights, less deep, middle shadows, whilst the deep shadows 
appear in their natural strength. With the removal of the 
lineature from the sensitive plate, on the other hand, the ratio of 
tones for the whole image, as well as for the details, is displaced. 
In the first place we shall obtain a picture which contains more 
contrasts of black and white. The light tones become considerably 
lighter by the reduction of the shadows. The dark parts, on the 
other hand, attain full vigour. In the first place, therefore, the 
original has to be considered as regards the distance of the 
lineature from the sensitive plate. Obviously, therefore, no 
accurate directions can be given in a case where feeling and 
experience are required. Next to the original, the number of the 
lines on the screen has to be considered. As a rule, one uses 
lineatures with five or six transparent and opaque lines to the 
millimetre (= 125-150 to the inch), and for these a distance of 
i to 1 mm. (= iV" 2 ?th inch) from the sensitive plate is gener¬ 
ally sufficient for most cases. With a less number of lines the 
distance can be increased. 

Autotypy is a process in which unprintable half-tones can be 
broken up by the use of a well-defined physical law into a 
mathematically determined grain, and the size of the grain can 
also be regulated to a certain extent with certain precautions. 

It is, therefore, easily understood that the autotypic process is 
now very general and most used, and not only in the limited 
department of photo-lithography, but in a more extended way, 
does excellent service for the preparation of illustrations of all 
kinds, for the simplest picture for the daily paper as for the 
finely-printed magazines and journals, for simple monochromatic 
printing, and for the highest colour printing. 

With accurate knowledge and command of the technique of 


74 


PHOTO-LITHOGRAPHT. 


photography and lithography, there is required before everything, 
for successful work, a faultless screen plate. The indispensable 
requirements which must be found in the screen are absolutely 
opaque black lines and bare glass in the white lines. The home 
preparation of such a screen plate is a somewhat difficult matter, 
and will not be absolutely successful if one has not a faultless 
ruling machine, a composition which is thoroughly opaque, which 
adheres well to the glass and gives clean, sharp lines in ruling, 
and which does not chip, and it will require a tremendous expen¬ 
diture of patience and perseverance. Glass screens of excellent 
quality may now be obtained commercially. 

For reproduction of the very highest quality, a drawn and 
etched screen plate is more suitable than one merely ruled on 
pigment, which never gives such sharp results. 

From various firms etched screen plates may now be obtained 
either as single or crossed-line screens, which fulfil all require¬ 
ments. 

The best screen to use is one with five or six opaque and 
transparent lines to the millimetre, which corresponds with 
2,500 to 3,600 points to the square centimetre. The above 
number of lines will suffice for nearly all work, and such screens 
give reproductions in which the grain is no longer visible to the 
naked eye, but appears as a closed tone. It is not advisable to go 
beyond this number of lines, except in special cases, when the 
details of the drawing in the original are specially small. With 
a smaller number of about three or four lines to the millimetre, 
too coarse a grain results, of which the individual points become 
too plainly visible, and these are distracting and act roughly, and 
do not accurately reproduce the gradation of tone. 

The best proportion between opacity and transparency is 1 : 1. 
From this is obtained, according to my opinion, the most beautiful 
and restful tones. It must also be remembered that the opaque 
spots actually lose considerably in strength in the brighter 
portions of the picture by the spreading action of the light. 

The printing may be done on bichromated gelatine paper, 
with which, however, extremely accurate inking up of the print 
is essential, and the prints must not have too much ink and must 
be very carefully printed. If, however, very good, clear negatives 
are used, either of the direct printiug methods, as already 
described in Chapter IV., is to be preferred. (See No. 4 Supple¬ 
ment.) 

2. Photo-lithographic Processes in which the Grain is not 
Formed During the Exposure. 

Of the many existing processes by which the breaking-up of the 
half-tones into printable lines or grain is effected, not in the 
negative, but subsequently by mechanical and chemical action on 
the stone or plate or the transfer film, I will only mention those 


THE COLOUR PRINTING PROCESS. 


75 


which appear to me to be the most important, the new methods 
which have already found firm footing in practical work or which 
appear likely to do so. All the older processes, which were either 
never actually successful or have been superseded on account of 
difficulty of working, we may properly pass over. 


(a.) The Patent Asphalt Process of Orell, Fussli, and Co. 
used for the Preparation of Colour Prints. 

I have already mentioned that the use of light sensitive 
asphalt for the preparation of printing plates for the various 
branches is by no means new. 

The fundamental principles of the well-known processes we find 
also used in the process of Orell, Fussli, and Co. 

The grained stone is coated with a thin film of light-sensitive 
asphalt, the composition of which we have previously learnt, and 
exposed under a reversed or stripped negative. The image after 
correct exposure is developed, and then, according to the construc¬ 
tion of the asphalt, in combination with the graining of the stone 
and the developer, there is formed a finer or coarser grain, or a 
closed or open image. 

The development is effected with petroleum, to which one-fifth 
or one-sixth of its volume of benzine is added, or with turpentine 
alone. Development takes place rather rapidly, and after a short 
time the image appears on the stone. The print is then treated as 
was suggested in asphalt printing; the stone is first gummed, and 
then by rolling up with ink and etching rendered suitable for 
printing. The pictures produced by this have a very fine grain 
and are in appearance very much like good collotypes; still twc 
or more tones are necessary to obtain an absolutely closed and 
vigorous action. 

Very similar to Orel and Fussli’s process is the following, also 
patented. 

(b.) The Colour Printing Process of Wezel and Naumann of 
Reudnitz, Leipzig. 

In this process also all the colour stones of a chromo picture are 
produced from a single stripped and reversed negative which is 
taken of the original. For the preparation of any colour stone 
there are three distinct stages. The first stage is the exposure, 
the second the development, and the third the development con¬ 
tinued still further, and any necessary small help by the litho¬ 
grapher. In each stage a special mode of treatment is required, 
according to whether the stone in question is to be used for a light, 
a more vigorous, or full colour. The stones for grey and the light 
blue or light red inks—thus those for many surfaces, but with few 
details—are treated differently to those for yellow, the second red 


76 


PHOTO-LITHOGRAPHY. 


or blue ; and these, again, differently to those for brown or quite 
dark colours. 

Everyone only slightly conversant with colour printing knows 
that the first plates are used for the general tones of the picture, 
and contain, therefore, tew details, and with the exception of the 
highest lights are tolerably full ; the latter plates, on the other 
hand, which are devoted to the darker colours, contain less toned 
surfaces, but, on the contrary, more details of the drawings. 
In order to attain this correctly the three stages of the produc¬ 
tion of the plates are carried out with this end in view. 

It should still be mentioned that the more or less fine graining of 
the stone determines the general ratio of the grain of the picture. 

The first stage is the exposure of grained stone coated with 
asphalt. With longer or shorter exposure it is possible to make 
the asphalt film more or less soluble, that is to say, to make the 
same more or less capable of resisting ethereal oils. 

It is therefore possible at this stage, by long exposure of the 
asphalt film, to give to the colour stone for bright colours more 
tone and less details. The stones for the darker inks are printed 
for a shorter time, and the asphalt film is less capable of with¬ 
standing the solvents, and the resulting plate contains less tones 
and more details. Finally, the plates for the deep colours are 
normally printed; the asphalt film is still less resistant, and con¬ 
sequently the stone will only have tone and details on those places 
which in printing ought to be the darkest. 

It is possible, therefore, by correct manipulation of this opera¬ 
tion, to obtain approximately the correct colour plate. 

There is, however, in the second process a corrector for the first. 
The development may be so performed that by the longer or 
shorter use of strong solvents, Hungarian or Russian turpentine, 
more or less of the asphalt will be dissolved. Thus if a slight 
error is made in printing it can be made good in developing. As 
a rule, the stones for bright colours, which consist of many tones, 
are not developed so long as those for the stronger colours. The 
actual stones for the deep colours are very strongly developed, so 
that almost all the delicate parts of the picture disappear, and 
only the dense strong parts remain on the stone. 

Still the fine details which are to be found in the vigorous 
parts, and which cannot be recognized, must be brought out. The 
fine parts of the drawing must be quite clear if the details are to 
be recognized, or the picture will be a fuzzy copy of the original, 
wanting in structure. 

This fault is remedied in the third stage of the treatment, in 
which a strong development of the picture is effected with strong 
acting oils or benzole and turpentine. As this operation, how¬ 
ever, would also wash away such delicate places which ought to 
remain on the colour stone, they must be covered with solution of 
gum and allowed to dry. Then those parts not covered with gum, 


J. BARTOs’ PROCESS. 


77 


in which the details of the image cannot be seen, are painted for a 
longer or shorter time, as maybe required, with a brush dipped in 
the developing solution, and when correctly developed may be 
covered up. The lighter places are treated for a shorter time, the 
very dark places for a longer time. 

By this treatment the particular parts of the picture become 
lighter and lighter, the details appear more and more; and, 
finally, the whole picture shows as it should do. Then the gum is 
washed off and the stone subjected to the already described treat¬ 
ment, so as to make it suitable for printing in quantities. Finally, 
the lithographer can make corrections with a needle or tusch. 

This process may be used, therefore, to prepare colour-printing 
plates from a negative obtained in the camera from an oil paint¬ 
ing or any coloured original. 

The negative for this process must contain all the details very 
clear, must be soft, and not be too dense. 

The different colour plates are thus in this process obtained by 
long or short printing, by strong or weak developing, and finally 
the details in the dark plates are obtained by separate develop¬ 
ment and covering up the other places with gum. 

The breaking up of the half-tones into printable grain is effected 
by graining the stone, before coating with the light sensitive 
asphalt film. On the finer or coarser graining of the stone depends 
also the structure of the grain of the image. 

This process yields the most beautiful results with correct 
manipulation, and in the hands of an expert photographer and 
lithographer is a valuable aid to the preparation of colour plates. 
The process is patented. 

(c.) J. Bartos’ Process for Preparing Photo-lithographs and 
Phototypes in Grain and Half-Tone. 

Bartos’ process belongs to those in which the breaking up of the 
half-tones into a printable grain is effected subsequently on the 
plate or stone by mechanical means. This is attained in a very 
original manner by means of a sandblast, which makes the half¬ 
tone printable. We have here not the breaking up of the half¬ 
tones in a mathematically regular manner, dependent on optical 
laws, as is the case with autotypy, but a method similar to that of 
Pretsch, which obtains the printable grain by reticulation of the 
chromated gelatine film, or other discoverers who attain the same 
result by asphalt dusting or some other means. 

For this process a well-polished litho stone or zinc plate is coated 
with a thin film of varnish, composed of— 


Chloroform 

... 

... 


... 300 g. 

Mastic 

... 



5 „ 

Asphalt ... 

... 



... 10 „ 

Benzole ... 


... 

... 

... 300 „ 

Linseed oil 

... 

... 

•• 

... 2 „ 







78 


PHOTO-LITHOGRAPHY. 


On the stone or plate thus prepared is transferred a carbon image 
in half-tone. 

This pigment film, when completely dry, is flowed ov r er with a 
mixture of— 

Glycerine ... ... ... ... 35 g. 

Water .25 „ 

Alum ... ... ... ... ... 2 „ 

and this should be allowed to act for about five minutes and then 
removed with blotting-paper. After this operation the pigment 
image can be easily destroyed. The pigment image is now ex¬ 
posed to the action of a weak sandblast. The sand acts on the 
relief image and gradually destroys it, and so that the film of var¬ 
nish underneath is gradually grained. 

After the pigment film has been removed the picture shows in 
all its details in grain on the varnish of the stone or plate. The 
image is now visible on the film of varnish, according to the 
strength of the tones in partial graining, and can be etched into 
the stone or plate. 

This is effected by etching with phosphoric acid — 

Water .. ... ... ... ... 100 g. 

Phosphoric acid... ... ... ... 4 „ 

When the etching solution has acted for about two minutes, the 
stone is washed and coated with a solution of gum— 

Water ... ... ... ... ... 100 g. 

Gum arabic ... ... ... ... 5 „ 

and allowed to dry. 

Then the film of varnish is removed with a pad of cotton wool 
damped with turpentine, the dry stone rolled up with litho ink, 
damped, and the excess of ink rolled off. The picture now shows 
with all its finest details on the stone, and can be printed. 

In preparing a relief printing plate the film of varnish forms the 
resist for the first etching. It is then rolled up and etched in the 
usual way. 

For preparing larger pictures on stone or metal plates, in which 
the grain must be coarser than with small pictures, the fully- 
developed and still damp pigment image is dusted with powdered 
resin and the film allowed to dry with the powder adhering to it. 
The pigment image thus dusted is treated, as previously described, 
with alum and glycerine, exposed to the action of the sandblast, 
and then etched with phosphoric or nitric acid. 

As the soft pigment film receives a grain by the dusting, this is 
reproduced of the same size by the action of the sandblast on the 
film of varnish on the stone or plate. 

The principal points of this process of preparing photo-litho¬ 
graphs or phototypes in half-tone, with a grain, are as follows :— 

1. From the photographic negative a pigment image is taken 


LTTUO-H ELIO GRAVURE. 


79 


and transferred to a litho stone or zinc plate, which has been pre¬ 
viously coated with varnish. 

2. The pigment image is then exposed to the action of the 
sandblast; and 

3. Then the pigment image is removed, and the image obtained 
on the film of varnish is etched. 

In the K.K. Hof uud Staatsdruckerei plioto-litbographs as well 
as phototypes have been prepared with excellent results by this 
process. The former in result are similar to the productions of the 
Orell and Fiissli process, and the latter were noticeable for good 
gradation. On the other hand, it cannot be denied that this pro¬ 
cess, which is patented, has been already surpassed by autotypy, 
which is far simpler and easier to work, and is founded on a 
scientific basis. 


(d.) Liteo-heliogravure. 

This process, invented by Chas. Eckstein, of Hague, the general 
director of the Topographical Bureau of the Royal Netherland 
General Staff, also belongs to those jDrocesses of photo-lithography 
by means of which any picture in half-tone can be reproduced. 
The breaking up of the half-tones is effected, as with the autotypic 
methods, by the use of a lineature, but instead of this being done 
in the photographic exposure, it is effected direct on the stone 
before the transfer of the photographic image. In this particular 
process the stone itself is not coated with a light sensitive film and 
printed on direct, but the ruling is made on the stone, and then a 
negative pigment image—a diapositive—is transferred to it exactly 
the same as with photogravure on copper. A further feature is 
that the result is not an ordinary transfer stone result, but an 
intaglio etched stone, which is printed from the depressions. 

For this original process the basis is a ruled pattern stone, 
prepared with great care and accuracy. For preparing this a grey 
stone of the best quality should be taken, and one without any 
chalky spots, crystals, or holes. This should be polished with a 
coarse cloth and oxalic acid solution till it has a very high polish. 
On the highly-polished stone-surface is spread a very thin but even 
film of asphalt. 

The solution is composed of— 

Asphalt... ... ... ... ... 5 parts. 

White wax ... ... ... ... 6 „ 

Stearic acid ... ... ... ... 6 „ 

This mixture is boiled, and to it whilst boiling is added in 
drops a solution of two parts of soda. When cold this mixture, 
which is fairly hard, is dissolved in about an equal volume of tur¬ 
pentine, filtered and kept in bottles for use. 

A sufficient quantity of this asphalt solution, which must not be 
sensitive to light, is poured into the middle of a levelled stone and 


80 


PHOTO-LlTHOGRArHY. 


distributed by means of a lithographic ink roller, which must not 
be used for any other purpose but this, till the coating is absolutely 
even aud shows a light brown colour. 

When this film has become quite hard, fine parallel lines are 
drawn over the whole surface of the stone with a very accurate 
working ruling machine, by means of which from five to ten lines 
per millimetre can be ruled. 

When the ruling is finished the stone is given a margin of wax, 
and quickly and evenly flooded with the following etching fluid— 

Pure nitric acid ... ... ... 0’16 parts. 

Alcohol 36 per cent. ... ... 0 60 „ 

Water ... ... ... ... 35 „ 

And, watch in hand, is etched for about half-a-minute. 

Instead of the above a solution of — 

Grlacial acetic acid ... ... ... 2 g. 

Water ... ... ... ... ... 100 „ 

may be used and allowed to act for half-a-minute. The stone is 
then well washed under a strong stream of water, allowed to dry, 
and covered with linseed oil. After about five minutes the whole 
of the stone may be washed with turpentine. Then it should be 
inked up with a pad, care being taken that all lines take the ink 
well and evenly. This pattern stone serves as the original plate 
for the subsequent ruled transfer. 

From the original ruled stone can be made, according to the 
nature of the original, a single, double, triple, or four-fold transfer. 

For preparing a stone with a ruled transfer, a smoothly ground 
stone well polished with oxalic acid is evenly coated with sensitive 
asphalt solution. On this, when dry, the desired single or crossed 
transfer from the original stone is made, and dusted with bronze 
powder. This adheres to the lines of the pattern, and in combi¬ 
nation with the printing ink protects the asphalt film underneath 
from the action of light. During the subsequent exposure, which, 
according to the sensitiveness of the asphalt and intensity of the 
light, can last from a half to two hours or more, the particles of 
asphalt not covered by the bronze powder become insoluble, whilst 
the protected parts preserve their solubility. 

After correct exposure the surface of the stone is carefully 
washed with a tuft of cotton wool soaked in oil of turpentine, 
when the particles of asphalt underlying the bronzed lines dis¬ 
solve. The stone at these parts is laid quite bare, and therefore 
made capable of being subsequently etched. The deep etchiug of 
the pattern is effected in the same way as was suggested in the 
preparation of the mother pattern stone. 

By this method a positive pattern is obtained, that is to say, the 
jlines print, and the impression shows therefore a black network. 

A second method of making a pattern transfer consists in 
making a pull from the original stone on to chalk transfer paper. 


L1TH0-HELI0GRA.VURK. 


81 


This pull is then damped on the back, and when just properly 
damp is laid on the polished stone (without any asphalt) and the 
transfer made. In order to remove the chalk paper without 
damaging the pattern the stone is covered with warm water, when 
the lines will dissolve. The simple pattern will now be found on 
the stone, which should now be well washed, then dusted with 
resin powder, which should be melted on with ether vapour. 
Then if the direction of the first lines was vertical, the second 
transfer is arranged with the direction of the lines horizontal tc 
the first, and there is thus obtained a simple crossed pattern. 
With four-fold crossed patterns the subsequent pulls are made in 
opposite diagonal directions. After each transfer the stone is well 
washed, allowed to dry, then dusted with resin powder, and with 
ether melted on to the pattern. 

The stone is now deep etched with dilute nitric or acetic acid 
and covered with linseed oil. 

By this method a grain instead of lines is obtained. By 
polishing the stone and transfering on to it, as well as by etching 
the places not covered by the ink, we have the pattern reversed, 
that is to say, it is converted into grain. 

For further operations of litho-heliogravure a very clear and 
soft negative is required, from which a glass transparency is 
taken. Under this transparency pigment paper sensitized on a 
20 per cent, solution of potassium bichromate is printed to 8 or 10 
degrees Yogel. Printing must be very carefully performed, as 
with under-printing too many details are lost. The exposed 
pigmented paper is washed in cold water, laid film side down on 
the previously prepared stone, and pressed into contact with an 
india-rubber squeegee. It should then be allowed to dry in a not 
too dry or too warm place. 

The stone should now be placed in a trough with warm water 
of about 40 to 45° C., and care should be taken to obtain water of 
as even a temperature as possible. After about five minutes the 
paper will be free from the stone, which should remain in the 
bath and be developed so long by shaking in order that the water 
may flow evenly over it till the image appears quite distinct ; a 
negative image is thus obtained on the stone. The film is then 
allowed to dry spontaneously for four or five hours till the pig¬ 
ment image has become quite hard. 

For etching a solution of perchloride of iron of various strengths 
is used, 40, 37, 33, and 30° Beaume. With subjects very rich in 
tones all four will be used; with simpler subjects one or the other 
may be omitted. 

The etching will begin, as a rule, with the 40° solution. The 
ferric chloride will first dissolve the thin, hardened pigment film 
and then go through the open lines of the pattern, where it will 
attack the stone and etch the deepest parts. 

Slowly the ferric chloride dissolves also the thicker pigment 

a 


82 


PHOTO-LITHOGRAPHY. 


film—begins also to etch the stone there, but less deeply. To tell 
when the four solutions should be used in turn, as well as the 
correct moment to interrupt the etching, requires considerable 
experience. The 30° solution, the weakest of the ferric chloride 
solutions, is used last, and in consequence of the greater propor¬ 
tion of water possesses a solvent power for the whole of the light- 
hardened pigment film. Accurate directions as to how long the 
etching with the different solutions is to be continued cannot be 
given, as this depends upon the character of the subject as well as 
upon the thickness of the pigment image. It may be always 
assumed, however, that any individual etching ought to last under 
no circumstances longer than three to four minutes. With well- 
covered stones the first etching should not be allowed to act so long 
as the last, and vice-versa, with less covered stones. 

As soon as the image shows the correct character through the 
etching solution the stone should be brought under the tap in the 
trough and quickly washed with clean cold water. The surface of 
the image should then be flowed over with oil of turpentine in 
order to remove the asphalt and gelatine film, and finally well 
washed with the rose and allowed to dry. The picture will be 
found deeply etched into the stone. The stone is now smeared 
over with linseed oil, inked up, and further treated as in ordinary 
lithogravure. 

In this process the negative pigment image is transferred to the 
stone and the printing image prepared by etching; the formation 
of the grain is produced by the pattern printed either on a 
polished stone, when it is converted into points, or the transfer may 
be effected on to an asphalted polished stone, when a network of 
lines will be obtained. 

For dark subjects the latter process is better, for lighter sub¬ 
jects the grain. 

Printing from such a plate has more similarities with etching 
printing than from stone; the effect of the ink is very good and 
expressive. 

Various pictures executed by Eckstein and in our establishment 
in one or more colours have proved the value of this process in 
practice. 

The foregoing are the different photo-lithographic methods for 
obtaining printing images in half-tone, and although in no way 
exhaustive, yet it appears to me that they are practically the most 
important. 


NEGATIVE TRANSFER WITH B1CHR0MATED GELATINE PAPER. 83 


APPENDIX. 

1. Negative Transfer with Bichromated Gelatine Paper. 

The properties of bichromated gelatine paper can also be very well 
used for the so-called negative printing, and this method offers 
many advantages. 

In order to convert a positive printing image into a negative 
various methods may be used ; the most convenient for the litho¬ 
grapher is the following:—A good litho stone is first ground in 
the ordinary way and then the surface rubbed with a pad and 
oxalic acid solution till it has a high glaze or polish. On to this 
stone is then transferred a sharp impression in a non-greasy ink 
from the positive printing image. According to the destination of 
the stone for large or small editions one of two processes may be 
adopted. If a thousand or more pulls are required from the stone 
the transfer may be dusted with resin powder, and this melted 
with the burning, heating, or ether process and the drawing etched 
in relief with 8 to 12° nitric acid and gum. Then the stone may 
be well washed with water and the acid removed with one to two 
per cent, acetic acid. 

For small runs the first etching is omitted, and the stone treated 
with acetic acid. In both cases the stone should be well washed, 
dried, and then coated with dissolved lithographic tusch or auto¬ 
graphic ink. The greasy substances of these materials penetrate 
into the surfaces of the stone that are laid bare, and firmly adhere. 
When the tusch or ink is completely dry the stone is washed with 
turpentine, inked up, and one now has a negative image from the 
subject in question, which shows all the original printing places in 
white and all white places black. 

The process of preparing such negative prints by the use of 
bichromated gelatine papers is much simpler. 

A sheet of gelatinized paper is sensitized for this purpose on a 
5 per cent, bath of potassium bichromate, squeegeed to a sheet of 
plate-glass and well dried, and on this is made with black ink, 
which is very opaque, in the dark or in gaslight, a sharp clean 
print. This print is then laid on a flat table, under a sheet of 
plate-glass, so that it cannot roll up, and exposed to the light for 
from five to thirty minutes. A long exposure rarely does harm in 
such cases, as the good opaque black ink allows no rays of light 
to pass through to those places which later should print white. 

The next manipulation is the development and inking up, which 
is done as in ordinary photo-lithography. In this operation all 



84 


PHOTO-LITHOGR A PH Y. 


those places which were not covered up by the printing will take 
the developing ink ; on the other hand, those places where the im¬ 
pression was will wash out clean and white. The print has 
assumed the appearance of a photographic positive. The print is 
now treated like any other photo-lithographic print, and finally 
transferred to a stone or zinc plate. This method is distinguished 
by its simplicity and safety ; it has also the advantage that any 
desired printing subject can be directly transferred in negative 
form to a zinc plate for relief etching, which otherwise could only 
be done by preliminary transfer to stone and subsequent transfer 
to zinc. 


2. Photo-autography. 

DRAWING WITH AUTOGRAPHIC INK OR LITHOGRAPHIC CHALK ON A 
CYANOTYPE, SALTED OR OTHER PRINT PROM A PHOTOGRAPHIC 
NEGATIVE OR POSITIVE. 

By autography we understand that method of reproduction by 
which any writing or drawing is made on a prepared or not pre¬ 
pared paper with greasy ink, tusch or chalk, which is subsequently 
transferred to stone or zinc for printing, or to zinc plates for relief 
etching. 

Autographic drawing papers differ for the different purposes, 
and for writing and simple line drawings smooth hard post paper 
is used, and lined transfer paper for fine pen or chalk drawings. 
The latter are prepared commercially by Angerer and Goschl. 
Very beautiful grained drawings can also be made for transfer on 
pyramidal grain paper. The proof for such drawings is usually 
done with lead pencil or red chalk, or it may also be made on a 
gelatine proof. 

In order to obtain fully and completely the character and correct 
reproduction of the drawing, without special expense of artistic 
help, it* is advisable to use a photographic print as proof. Ik 
should be noted that for pen drawing on smooth paper with greasy 
tusch or ink, for chalk drawings on a prepared grained paper done 
as previously mentioned, with greasy lithographic chalk, the 
drawing should be transferred direct to zinc or stone in order to- 
save having to make subsequently a photographic print. 

If a pencil, red crayon, or other proof is used for an autographic 
drawing on paper with the idea of transferring it direct to stone 
or zinc, a suitable photographic print may also be used on suitable 
paper without any disadvantages. 

For the prints all photographic papers without glaze, such as 
ordinary plain salted paper, Eastman’s positive bromide paper,, 
and others, may generally be used. Glossy or albumenized papers 
are not suitable for this, as the ink runs, and does not form solid 
clean lines. 


P. IOTO-AUTOGRAPHY. 


85 


The best of all, however, is cyanotype paper, as even with very 
deep printing it keeps the details in the shadows open, and on 
account of its blue tones is more suitable for the subsequent 
drawing with black tusch. When, however, prussiate paper 
is not handy, and subjects with fewer shadows and less details 
are to be treated, any of the other papers above-mentioned may 
be used. 

If ferro-prussiate paper is to be used, the same may be prepared 
as recommended on p. 23. 

The so-called salted or plain paper is prepared as follows: — 
A sheet of well-sized post paper is first bathed in a solution 
of — 

Ordinary salt ... ... ... ... 1 part 

Water ... ... ... ... ... 25 parts 

and then sensitized in a solution of silver nitrate 1 : 12. It is 
printed till the print has assumed a fairly full brown tone, and all 
the details in the shadows are well printed out. It should then 
be toned in the following toning bath:— 


Distilled water ... ... ... 1000 g. 

Sodium acetate (twice fused) ... 15 „ 

Solution of gold chloride (1 : 100)... 25 „ 


till the print has assumed a deep dark brown tone. It should 
then be fixed in a solution of sodium hyposulphite, 1 : 15. It 
should be printed rather deep, as in toning and fixing the image 
loses in depth. It is moreover unnecessary in this case to make 
a beautiful print; the chief thing is only that all details of the 
image should be clearly seen. The print is then well washed 
in frequent changes of water and then dried. 

The print on Eastman’s bromide paper is prepared as fol¬ 
lows :— 


Red light must be used. It should be printed by an ordinary 
gas flame at a distance of about 50-80 cm. (=24 to 36 ins.) for 1 
to 20 seconds, according to the density of the negative. Here 
again a technically perfect print need not be arrived at, but one 
which contains all the details very clear. Under a good trans¬ 
parent negative a useful image for the artist will be obtained with 
about two seconds’ exposure. 

The developer is composed of two solutions 


(A.) Water. 

Neutral oxalate of potash 
(T».) Water ... 

Sulphate of iron 
Concentrated sulphuric acid 
Or glacial acetic acid ... 


500 g. 

165 „ 

50 cm. 
15 „ 

2 drops 
5 „ 


Three parts of solution k. and one part of solution B should be 








86 


.’H0T0-L1TH0GRAPHY. 


mixed together. As soon as the shadows have attained the desired 
tone, the prints should be placed in reveral fresh baths of 


Water ... 

... 200 

ccm. 

Acetic acid 

1 

drachm. 

Sat. sol. alum... 

... 50 

g- 

washed and fixed in a bath of 



Water ... 

... 50 

ccm. 

Sodium hyposulphite... 

... 10 

g- 


tor about ten minutes. Then well washed and dried. 

For pen drawings all not gelatinized or albumenized printing 
papers may be used as already mentioned. The chief thing is that 
the paper should be well-sized and of good firm texture. If prepared 
grain paper is used, which is provided with a film of chalk, kaolin, 
or any other white colouring matter combined with gelatine, and 
on which film the grain is impressed, only prussiate prints can be 
used. The paper is sensitized as previously described, only it is 
advisable not to leave it too long in the solutions, or else the film 
may become softened. The film will also dissolve in hot water at 
about 80° C. 

The prints as soon as dry can be used for drawing on. On the 
grain papers the outline may be drawn with the pen and be shaded 
with chalk, or it may be drawn with chalk only. With unprepared 
papers it is advisable to coat them with a thin solution of boiled 
starch, as then the transfer to zinc or stone is most exact. The 
drawing may also be left a long time without spoiling. The coat¬ 
ing is performed with a pad dipped into the liquid, which consists 
of one part of fine bookbinder’s starch and four or five parts of 
water, and passed several times over the print. 

The drawings ought only to be done with greasy lithographic 
tusch or chalk or autographic ink, which consists principally of 
greasy materials and lampblack. For pen drawings hard pens 
should be used, and care must be taken to make thick strokes. 
Only a little tusch or ink ought to be taken into the pen, so that it 
does not run out, and thus clean, sharp lines be obtained. If this 
be observed very close shadings and cross lines can be produced 
clean and neat. 

When the drawing is finished and the tusch or ink has become 
dry the same should be laid between damp blotting-paper, and 
meanwhile a clean ground, and dry pumiced stone worked in the 
press and the pressure correctly adjusted. As soon as the draw¬ 
ing has become moderately damp right through, and the paper feels 
soft without being wet, it should be laid with the image down¬ 
wards on the stone and transferred to the same with strong 
pressure. After repeated working the paper will adhere firmly to 
the stone. In order to loosen it the stone should be covered with 
hot water of abwit 80° C., when the film will dissolve and the 
paper become quite free. Any exertion of force must in this 


L1TH0GRAVURE. 


87 


operation be quite avoided, and the paper must not be pulled off 
with violence. All, even the finest lines, will have been trans¬ 
ferred to the stone. The stone is now gummed, if possible allowed 
to stand for some hours, and then etched with a gum etching solu¬ 
tion of two degrees’ acid strength, or later etched in relief, and is 
ready for printing. If the transfer is made to zinc, for printing 
from this the plate is treated as suggested on p. 6. If, however, 
a relief etching for the typographic press is to be prepared of the 
subject, the transfer is made on to a smooth polished zinc plate. 


3. Lithogravurk. 

With this particular process an intaglio printing stone or 
intaglio printing plate is prepared by chemico-physical means. 

This process was discovered and brought to great perfection by 
Chas. Eckstein, the general director of the Typographical Bureau 
at the Hague, and offers especially many advantages for the repro¬ 
duction of maps. 

A map engraved, drawn, or transferred on stone, or written in 
on copper, in originally one colour, can by this process in a com¬ 
paratively easy way be converted into a many-coloured print; 
this process can also be used very advantageously for changing 
the names for the places—rivers, mountains, etc. In the first place 
intaglio original printing plates in all the colours can be prepared 
which can then be printed for further reproduction; in the second 
case it is necessary to re-engrave the network, hydrography, etc., 

When it is desired to convert a monochrome image into a multi¬ 
coloured map, as many stones as there are colours to be used must 
be first ground and polished with oxalic acid till they have a high 
polish. 

In the meantime an asphalt or other light-sensitive solution 
should be prepared, with which the stone is coated in the dark 
very evenly, and somewhat more than is done for a photo-litho¬ 
graphic print. 

The asphalt solution is composed of — 

Syrian asphalt ... ... ... 20 g. 

Chloroform ... ... ... 300 g. 

Benzole ... ... ... 100 g. 

Oil of lavender ... ... ... 20drops. 

After it has been dried in the dark the impression from the 
black plate, which should be previously made on transfer paper, is 
transferred to the asphalt film as previously laid down, and before 
it is dry dusted with bronze powder. All lines, titles, or figures 
which should not appear on that particular colour-plate must be 
then covered with the above asphalt solution, and only those places, 
for example, on the one plate all titles, on another all the roads, on 
a third the river courses, and so on, should be left, all of which 
later should appear in printing. 


88 


PH OTO-LITHOG RA PH Y. 


The stone is now, according to the sensitiveness of the film and 
the strength of the light, exposed for from fifteen minutes to two 
hours. Over-printing, if it is not very exorbitant, does not do any 
harm with the stronger letters or lines on account of the good 
covering. With very fine lines, however, more care must be taken. 
If there is any doubt as to the length of the exposure a test may be 
made at one corner of the plate with a pad dipped in rectified 
turpentine. When the asphalt will no longer dissolve the exposure 
may be discontinued. With some experience the photometer may 
also be used. 

Then the whole surface should be washed with rectified turpen¬ 
tine and a pad of cotton wool, when the ink lying under the bronze, 
that is, the lines where the asphalt has been protected from the 
action of light dissolve, and the surface of the stone appears. The 
rest of the asphalt film has become insoluble from the action of 
light, and now forms the etching-ground for the reversed negative 
image on the surface of the stone. 

When the stone has been well washed with water it may be 
etched, which is don© with glacial acetic acid two parts, water 100. 
When there are any fine lines in the drawing the etching is in¬ 
terrupted at the end of two minutes, and they should then be 
covered with tusch, and then when the tusch is dry the other 
parts are further etched for a longer or shorter time according to 
the degree of fineness. In any case the time of etching should 
not exceed five minutes. The stone is allowed to dry and then 
coated with a solution of tusch or linseed oil, which penetrates 
into the etched parts and makes them capable of taking ink. 
After about ten minutes the whole stone should be washed with 
turpentine or benzole, by which the etching ground is removed, 
when the stone is inked up like an ordinary gravure. 

In this way is obtained a stone with deep etched drawing, 
which according to the blocking contains the titles, the rivers or 
roadways, and from which subsequently the necessary gravures 
can be taken. This stone can either be used for direct printing 
or it may be used as an original stone from which the necessary 
transfer can be made. 

The same process may also be made for intaglio printing plates 
on zinc or copper, only then the etching must be done with nitric 
acid or ferric chloride. 

Instead of the transfer on the light sensitive film, a drawing on 
transparent paper may be used, or a photographic transparency. 
The exposure in this case, as the opaque ink and bronze powder 
are not used, must be very carefully estimated. 

The advantage of this process is that an intaglio printing 
surface may be obtained so that engraving is entirely or partially 
avoided, and that this printing surface may be used as an original 
from which the reproductions are made. 





INDEX 


Acid, Acetic 
- Citric 


Gallic . 
Hydrochloric 
Nitric 
Oxalic . 
Phosphoric 
Sulphuric 


Action of Lineature . 
Albert's Photo-litho Paper 
Albumen Process . 
Angerer & Goschl . 
Asphalt . 

- Process . 

-Husnik’s 

-Valenta’s 

Autographic Ink 
Autotypy 

-Negative . 


PAGE 

IO 

IO 

IO 

9 

9 

io 

IO 

9 

69 

56 

64 

25 

17 

60 

60 

61 

7 

67 

41 


Galls, Tincture of 
Gelatinizing Paper . . . 

General Notes on Photolitho¬ 
graphy 

Gold and Mercury Intensifier 
Greasy Drawing Materials 
Gum Arabic . 

Half-tone, Breaking up . 

-- Photo-lithography . 

Hcbensperger’s Process . 
Hubl’s Hydroquinone Intensi 
fier .... 

-Iso Emulsion . 

Husnik’s Asphalt . 

- Photo-litho Paper . 

Hydroquinone Developer . 

Indirect Transfer 
Inking up and Developing 


PAGB 

10 

47 


Bartos* Process 

# 

20, 77 

Intensification . 


3T 

Behaviour of Asphalt on 

Stone 8 

Intensifier, Lead 


40 




- Mercury. 


40 

Cadmium Intensification. 

. 40 

- Metol 


39 

Chromate Salts 

• 

. 48 

- Silver 


40 

Coating the Stone . 

• 

. 62 

- Uranium 


40 

Cold Melting Process 

• 

• 12 

Iodized Collodion . 


37 

Correcting Negatives 

• 

• 35 

Isochromatic Emulsion, Albert 

4 i 

Cyanotype Paper 

• 

. 24 

- Hubl . 

• 

43 

- Bleaching 

• 

. 24 





• 


Lemercier and Lerebours 

• 

16 

Dark Room, The . 

• 

• 34 

Line Drawings 


21 

Deep-etching Process 

• 

. 11 

Litho Chalk, Hard . 


r 

Developer 

• 

• 37 

- Soft 


8 

Developing Ink . 

• 

. 8 

- Stone . . . 

• 

4 

Direct Printing . 


. 60 

Lithogravure . . . 

• 

87 

- Transfer 


• *5 

Litho-Heliogravure . 

• 

79 ‘ 

Distance of Lineature 


• 73 

Lithography, Theory of . 


3 

Drawing on Blue Prints 


• 23 




-Prepared Paper 

• 25 

Making Direct Negatives 


36 




Mungo, Ponton 


17 

Eberle’s Process . 

# 

. 11 




Eckstein's Process . 


. 20 

Negative for Photo-litho . 


34 

Electric Lamps 

• 

. 3 i 

-Transfer with Paper 


83: 

Etching the Stone . 


. 10 

Negre .... 

• 

17 




Nicephore, Nie'pce . 

• 

16 

Failures in Transfers 

• 

. 58 




Fixing 

• 

• 38 

Orell and Fussli Process . 

20 , 

1 75 

Fox Talbot . • 


• l l 




Franz’s Paper. • 

• 

• 55 

Photo-Autography . . 

• 

84. 


49 

38 

6 

10 


20 

67 

66 

38 

43 

17 

S 3 

42 

16 




















INDEX 





PAGE 



FAG| 

Photo-Litho Transfer 

• 

• 

57 

Sensitizing Paper 

• • 

49 

Photometer 

• 

• 

5i 

Silver Bath 

• 

37 

Poitevin ; . . 

• 

• 

'7 

Stripping Negatives 

• 

45 

Prism . . . 

• 

• 

44 

Studio, The . . 

• 

30 

Printing . 

• 

• 

62 




-on Bichromated 

Gelatine 

50 

Tusch . . . 

• 

7 

Pvramidal Grain Paper . 


26 








Valenta’s Asphalt . 

• 

17 

Reproduction of Prints 

• 

• 

27 




- Size of . 

• 

• 

28 

Waterhouse’s Arrowroot Process 

66 

Reversed Negatives 

• 

• 

44 

Wezel & Naumann 

• 

75 

Sachets Fish-glue Process 

• 

66 

Zinc Plates 

• 

5 

Scamoni’s Process . 

• 

• 

12 

-Roughened . 

• 

5 

Scraper Boards 


• 

25 

-Oxidized . 

• 

5 

———-Schauffelen & Co. 

• 

26 













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3 X 

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No. 21 No. 29 No. 37 


SOLD BY 

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Other Samples furnished upon application 













































































































































































Fr. v. Lenbach pxt. 


W. Klechl sc. 


PHOTOLITHOGRAPH FROM A PEN AND INK SKETCH. 

FROM AN ETCHING PUBLISHED BY E. AUMULLER IN MUNICH. 


REPRODUCTION AND PRINT BY THE IMP. ROY. STATE PRINTING OFFICE IN VIENNA. 















IV 



POSITIVE PRINT FROM A PANTOGRAPH, 


REPRODUCTION AND PRINT BY THE IMP. ROY. STATE PRINTING OFFICE IN VIENNA 











































VI. 

















































































































































¥ 































































































y 









V 









































































